Boris Johnson has warned of a significant expansion in the number of coronavirus cases blighting the UK.
His comments come as the toll across Britain reached 39.
The prime minister said he believes it is “much more likely than not” that the UK will face a “challenge” from coronavirus in the coming weeks or months.
“The most important thing now is that we prepare against a possible, very significant expansion of coronavirus in the UK population – that’s clearly on the cards," he told the BBC.
“It is in my view much more likely than not that we will face a challenge in the weeks, months ahead…
“You’ve got to consider the realistic possibility that there is now going to be a significant expansion in the number of cases.”
The PM insisted the Government would do “everything we can” to “address the problem and to stop the spread of the disease”.
Asked if schools would be closed and big events cancelled, Mr Johnson said: “What we’ve got is a range of calibrated responses – the measures that you have mentioned are on that list.
“The issue will be when and how and with what logic to deploy them.”
Slovakia's Prime Minister Peter Pellegrini attends a news conference during the summit of the Visegrad Group (V4) countries to discuss response to the spread of the coronavirus, in Prague, Czech Republic, on March 4.
U.S. Vice President Mike Pence gives a news briefing about the coronavirus with members of the White House Coronavirus Task Force at the White House in Washington, D.C., U.S., on March 3.
The U.S. White House coronavirus response coordinator Dr. Deborah L. Birx attends a press briefing, as Vice President Mike Pence looks on, in the White House on March 2. As of March 3, six people had died in the state and at least 100 confirmed cases were reported across the country.
Government officials make phone calls to members of the Shincheonji Church of Jesus to check if they have symptoms of COVID-19, at the Goyang City Hall in South Korea on March 3. The country confirmed its 29th death and more than 4,800 cases of the virus infection on March 3.
A Brazilian scientists, who is among those that concluded coronavirus DNA sequencing, inserts a tube into a portable device connected to a computer that decodes virus DNA, at the Tropical Medicine Institute of the São Paulo University Medical School in Brazil on March 2.
Rescue workers wearing masks and protective clothing check a man's temperature during a mock drill on handling suspected carriers of the coronavirus, in Peshawar, Pakistan, on March 2.
Students of Hanoi National University of Education attend the first day of classes after returning to the university, which was closed for over a month due to the coronavirus outbreak, in Hanoi, Vietnam, on March 2.
U.S. President Donald Trump speaks during a news conference on the coronavirus outbreak as (L-R) U.S. Secretary of Health and Human Services Alex Azar, National Institute of Allergy and Infectious Diseases Director Anthony Fauci, U.S. Vice President Mike Pence, Director of the Centers for Disease Control and Prevention Robert Redfield and U.S. Surgeon General Jerome Adams look on, at the White House on Feb. 29.
A cleaner sanitizes a wagon on a regional train at the Garibaldi train station in Milan, Italy, on Feb. 28. Authorities are taking new measures against the COVID-19 outbreak as death toll in the country reached 21 on Feb. 29.
A researcher works in a lab that is developing testing for the COVID-19 at the Hackensack Meridian Health Center for Discovery and Innovation in Nutley, New Jersey, U.S., on Feb 28. The facility develops novel therapies for some of the worlds most difficult diseases.
U.S. Vice President Mike Pence speaks next to Health and Human Services Secretary, Alex Azar, during a coronavirus task force meeting at the Department of Health and Human Services in Washington, D.C., U.S., on Feb. 27.
A man wearing a face mask walks past an installation of the Olympic rings in Tokyo, Japan, on Feb. 28. The International Olympic Committee is "committed" to holding the 2020 games in Tokyo as planned despite the widening coronavirus outbreak, the body's president has pledged.
Umrah pilgrims are seen after the cancellation of the departure to Mecca following the Saudi government's temporary ban announced on Feb. 27, to keep the country safe from the virus outbreak, at Soekarno Hatta International Airport, in Jakarta, Indonesia, on Feb. 27.
A resident of Jongno-Gu district wearing a face mask sprays disinfectant as a precaution against the coronavirus at the Jogyesa Buddhist temple in Seoul, on Feb. 27.
School staff leave after the government announced a 14-day closure as they found a eight-year old student was infected with the virus, at Phraharuthai Donmuang School in Bangkok, Thailand, on Feb. 26.
South Korean President Moon Jae-in talks during a special government meeting to discuss measures to prevent the further spread of COVID-19, at the Daegu City Hall in Daegu on Feb. 25.
Fans wear masks at Stadio San Paolo in Naples, Italy, on Feb. 25, prior to the UEFA Champions League round of 16 first leg match between SSC Napoli and FC Barcelona.
Members of the Guardia di Finanza wearing face masks stop a car, amid a coronavirus outbreak in northern Italy, in Casalpusterlengo, Italy, on Feb. 24.
A reveler wears protective face mask at the Venice Carnival, the last days of which were called off after third death was reported in the country, in Italy on Feb. 23.
Buddhist monks wearing protective face masks pray during a blessing ceremony for the people affected by the COVID-19 outbreak, at a temple in Kuala Lumpur, Malaysia, on Feb. 22.
Members of Red Cross board a Colombian Air Force plane that will evacuate the citizens from coronavirus-hit China, at the CATAM military base in Bogota, Colombia, on Feb. 22.
French Economy and Finance Minister Bruno Le Maire speaks next to the Junior Minister for Economy and Finance Agnès Pannier-Runacher during a press conference after a meeting on the coronavirus' economic consequences, at the Economy Ministry in Paris, France, on Feb. 21.
A medical worker checks the temperature of a man wearing a protective mask at a quarantine checkpoint in the Son Loi commune in Vinh Phuc Province, Vietnam, on Feb. 20.
A Chinese tourist, who was tested positive for the COVID-19 coronavirus and isolated for treatment, gestures while accompanied by medical staff after she was discharged from the hospital following her recovery, near Colombo in Sri Lanka, on Feb. 19.
Passengers wearing protective facemasks amid concerns of the COVID-19 coronavirus outbreak wait to board their plane at Kuala Lumpur International Airport in Malaysia on Feb. 19.
Media personnel chase after a passenger (C) who disembarked from the Diamond Princess cruise ship at the Daikoku Pier Cruise Terminal in Yokohama, on Feb. 19.
Indians who were airlifted from Wuhan wait to collect their release certificates before leaving the ITBP quarantine facility in New Delhi, India, on Feb. 17.
Military medics stand in a formation after deplaning from a transport aircraft of the People's Liberation Army Air Force (PLAAF) at the Tianhe International Airport in Wuhan, China, on Feb. 17.
Pictures of Pakistani students studying in Wuhan, China, are displayed by their family members during a demonstration in Lahore, Pakistan, on Feb. 16. The family members are demanding the evacuation of their relatives.
A U.S. passenger gives a thumbs up to reporters while arriving at the Haneda Airport in Tokyo, Japan, on Feb. 17, after disembarking in Yokohama from the Diamond Princess cruise ship.
Nepalese nationals who were in Wuhan walk out from a Nepal Airlines plane at Tribhuvan International Airport in Kathmandu, on Feb. 16. The chartered plane brought back 175 nationals from Hubei province.
A woman is seen wearing a protective mask as she holds a rose on Valentine's Day, while waiting for the subway at a station during rush hour in Beijing, on Feb. 14.
Passengers and children stand on the deck of the cruise ship Diamond Princess, as the vessel's passengers continue to be tested for coronavirus (COVID-19), at Daikoku Pier Cruise Terminal in Yokohama, Japan, on Feb. 13. Aboard this quarantined ship, 219 people have tested positive with the virus.
Family members of Pakistani students studying in Wuhan, rally outside the Chinese Consulate in Lahore, Pakistan, on Feb. 13., for the evacuation of their children from the Chinese city.
Cambodia's Prime Minister Hun Sen (C) speaks to passengers on board the Westerdam cruise ship in Sihanoukville on Feb. 14, where the liner on Feb. 13 was docked after being refused entry at other Asian ports due to fears of the virus.
Jay Butler, deputy director for Infectious Diseases at the Centers for Disease Control and Prevention (CDC), speaks to the media inside the Emergency Operations Center in Atlanta, Georgia, U.S., on Feb. 13.
An employee receives payment from a customer through a container on a stick, in Beijing on Feb. 12. A ramp has also been set up to deliver food from the counter.
Members of the media stand near the cruise ship Diamond Princess, where dozens of passengers were tested positive for coronavirus, at Daikoku Pier Cruise Terminal in Yokohama on Feb. 11.
Workers produce protective clothing at a factory in Wuxi, China, on Feb. 8. The factory, which previously produced suits and sportswear, switched to production of protective clothing as demand increased due to the ongoing coronavirus outbreak.
Hong Kong Chief Executive Carrie Lam speaks to the media during a press conference on the coronavirus situation in Hong Kong on Feb. 8. Lam said that the government has bought 48 million masks and received 17 million more from China to counter the shortage of masks in Hong Kong.
Flight attendants wearing protective clothing and masks serve snacks to Canadians, who had been evacuated from China due to the outbreak of novel Coronavirus on an American charter plane, on another aircraft taking them to Canadian Forces Base (CFB) Trenton from the Vancouver International Airport in Richmond, Canada, on Feb. 7.
Taiwan's President Tsai Ing-wen speaks about the coronavirus situation during a news conference at the Centers for Disease Control in Taipei, Taiwan, on Feb. 7.
Members of an emergency team participate in a drill to prepare for the potential arrival of passengers infected with the coronavirus at the Viru Viru International Airport, in Santa Cruz de la Sierra, Bolivia, on Feb. 6.
Workers in protective gear are seen on Japan Coast Guard boats in Yokohama, on Feb. 5, bringing patients from the quarantined Diamond Princess cruise ship.
This handout photo released by Malaysia's Ministry of Health shows citizens being directed onto a bus by health officials as they arrive at the Kuala Lumpur International Airport in Malaysia in Feb. 4.
Health services staff members wearing protective gear interact with passengers at the Hamid Karzai International Airport in Kabul, Afghanistan, on Feb. 2.
Members of the Association for Sri Lanka and China Social and Cultural Cooperation (ASLCSCC) hold candles during a vigil to pray for people who are suffering from coronavirus across the world, in Colombo, Sri Lanka, on Feb. 1.
Turkish Health Minister Fahrettin Koca speaks to the press after a Turkish cargo plane carrying 42 passengers from Wuhan landed at Etimesgut Military Airport in Ankara, Turkey, on Feb. 1.
Officials make preparations in Turkish Air Forces' A400M cargo plane at Etimesgut Military Airbase in Ankara, which is to depart to China to fly Turkish citizens out of Wuhan, on Jan. 31.
China's U.N. Ambassador Zhang Jun stated in his press briefing that over 130 patients have been cured of pneumonia caused by the coronavirus in New York City on Jan. 31.
Thailand Prime Minister Prayuth Chan-ocha (C) speaks to journalists during a visit to Suvarnabhumi Airport to inspect measures in place to monitor passengers as they arrive in Bangkok on Jan. 29.
Children are seen wearing facial masks as a precaution after Nepal confirmed the first case of coronavirus in the country, at Matribhumi School in Madhyapur Thimi, Nepal, on Jan. 29.
(L-R) Sabine Hagenauer of the infection department at the 4th medical department of Kaiser Franz Josef Hospital, Michael Binder, medical director of the Vienna Hospital Association, and Judith Aberle of the department of virology, Medical University Vienna, address a press conference at Kaiser-Franz-Josef hospital in Vienna, Austria, on Jan. 26. A Chinese flight attendant was quarantined in the hospital with symptoms of flu, in what authorities suspected as the first coronavirus case in the country.
A Rospotrebnadzor (Russian Federal Service for Supervision of Consumer Rights Protection and Human Well-Being) official uses a thermal imaging device to conduct a temperature check of passengers arriving at Krasnoyarsk International Airport on a plane from Cam Rahn, Vietnam, in Russia on Jan. 23.
Director-General of World Health Organization (WHO), Tedros Adhanom Ghebreyesus, takes part in a news conference after a meeting of the International Health Regulations (IHR) Emergency Committee to discuss about the outbreak of Pneumonia in China and other countries due to the 2019-nCoV, in Geneva, on Jan. 22.
Kazakh sanitary-epidemiological service worker uses a thermal scanner to detect travelers from China who may have symptoms possibly connected with the coronavirus at Almaty International Airport in Kazakhstan Jan. 21.
Dozens of diggers work to build a new hospital in Wuhan, on Jan. 25. Due to the large number of infected people, the government decided to establish a temporary 1,000-bed hospital.
95/95 SLIDES
Earlier, Mr Johnson held an emergency Cobra meeting where ministers discussed a "battle plan" to be published on Tuesday.
Speaking afterwards he said: “We have also agreed a plan so that if and when it starts to spread, as I’m afraid it looks likely it will, we are in a position to take the steps necessary to contain the spread of the disease as far as we can, and to protect the most vulnerable.”
He added that the "single most useful thing we can all do to support the NHS is to wash our hands, two times to Happy Birthday, with hot water", and that people should otherwise go about "business as usual".
Government sources told the PA news agency it could be “months rather than weeks” before the outbreak peaks in the UK.
In a suggestion that extra emergency powers would not be required immediately, the source said: “We don’t want to have to take decisions before we have to. As much as possible we want people to carry on with their daily lives.”
Legislation allowing the Government to use extra powers to help control the virus is expected to go through Parliament by the end of the month.
Measures could include asking retired doctors and nurses to return to the NHS, urging people to work from home, closing schools, increasing class sizes and cancelling large public events.
In a piece for the Evening Standard on Monday , Health Secretary Matt Hancock said the Government was still working on containment of the virus in the UK, where people are identified and their close contacts traced.
Britain's Health Secretary Matt Hancock arrives at Downing Street in central London on March 2, 2020, ahead of an emergency COBRA meeting into UK's developing coronavirus COVID-19 situation. - Britain's Prime Minister Prime Minister will on Monday Chair an emergency COBRA meeting on the coronavirus outbreak, after the number of confirmed cases of COVID-19 in the United Kingdom rose to 36. (Photo by Tolga AKMEN / AFP) (Photo by TOLGA AKMEN/AFP via Getty Images)
“But we are realistic about the fact that globally cases are rising and we may not be able to rely on it forever, especially if coronavirus becomes more widespread in Europe,” he added.
“The next phase is delay. We will move to this phase if the global situation makes containing the virus impossible.”
Earlier, the European Commission raised the coronavirus risk level from moderate to high for those in the European Union and the UK.
One of the cases diagnosed on Monday was a worker at the North East London NHS Foundation Trust offices at Vinters Business Park near Maidstone in Kent.
Another is somebody from a secondary school in Torbay.
Some 13 new patients in the UK were diagnosed on Sunday, including a member of staff at Wimbledon College.
Globally, around 86,000 people have been infected, with more than 3,000 deaths.
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