© PA Asda is battling to fight off heavy competition from the rise of discounters Aldi and Lidl

Asda has reported a near 6% fall in sales at established stores, confirming its position as the worst performing major UK supermarket.

Sales at the Walmart-owned chain’s established stores dropped by 5.8% in the three months to 30 September. That was an improvement on the previous quarter, when sales were down by 7.5%, but puts Asda well behind rivals Tesco and Morrisons, which recently reported underlying sales growth.

Last week, Sainsbury’s announced a 1% fall in underlying sales in the 28 weeks to 24 September.

Walmart said the UK was the only one of its 11 international markets not experiencing growth at stores open for more than a year, as the number of shoppers fell by 4.2% year on year. Operating income also dipped in the UK. Shoppers spent 1.6% less on average on each visit.

Walmart’s chief financial officer, Brett Biggs, said: “The key priority remains driving an improved customer experience and building sales momentum by simplifying the offer, improving product availability and making strategic investments in service and price.”

Asda is trying to fight off heavy competition from the rise of discounters Aldi and Lidl, which have stolen its once strong position as the UK’s cheapest grocer. Asda only operates large outlets and has been unable to tap into the rise of convenience stores, unlike Tesco and Sainsbury’s.

It has also suffered from a number of recent upsets, including a card reader glitch that led to angry queues of customers in stores last month and a BBC Watchdog investigation that criticised Asda for dirty home delivery crates.

Sean Clarke, who stepped in to replace Andy Clarke as chief executive of Asda in July, said shopper numbers had started rising again over the previous quarter.

“We have lowered thousands of prices, improved hundreds of own brand products and invested in more hours for colleagues on the shop floor, so it’s encouraging to see more customers shopping with us in stores and online,” he said.

Consumer body Which? had found Asda to have the lowest prices on branded groceries for the seventh month in a row, recognising continuing price cuts at the supermarket, Clarke said.