© REUTERS/Neil Hall Britain's Chancellor of the Exchequer Phillip Hammond waits to greet Hong Kong's Chief Secretary for Administration Carrie Lam at 11 Downing Street in London

Chancellor Phillip Hammond will this week announce 1.3 billion pounds in new spending on roads as part of his plans to bolster the economy as Britain prepares to leave the European Union, the Treasury said on Sunday.

Hammond's first budget statement as chancellor of the exchequer on Wednesday will also commit to whittling down Britain's large budget deficit, but he will also carve out some flexibility to allow him to spend more and offset any sharp slowdown in the economy.

Britain's economy is so far faring better than expected after the vote to leave the EU, but growth is set to slow next year, limiting his options.

Measures to boost infrastructure and improve Britain's weak productivity growth will be at the heart of the chancellor's plan, the Treasury said, as Hammond aims to give some long-term support to the economy as Britain exits the EU.

Last month, the Confederation of British Industry urged a boost in public investment to 2 percent of economic output, or an increase of around 6 billion pounds a year.

The Treasury said it had identified quick-turnaround infrastructure projects and upgrades to existing networks that would help to relieve road congestion, easing the commute for millions and boosting productivity.

A spokeswoman for the Treasury said the money could be available as soon as the Transport Ministry wanted it.

Hammond will also announce on Wednesday details of support to families that are struggling to get by, the Treasury said, echoing a pledge by Prime Minister Theresa May to address the financial frustrations of many voters who chose to leave the EU.

The statement said Hammond's approach on the budget would be different to that of his predecessor George Osborne by limiting announcements to top-level spending decisions "rather than announcing full details of individual projects".

It said the Autumn Statement would provide "a stable economic platform as the UK leaves the EU, tackling the long-term challenges facing the country, while helping to build an economy that works for everyone".

An industrial strategy will be announced in the coming weeks, the Treasury added.

(Reporting by Elisabeth O'Leary; Editing by William Schomberg and Kevin Liffey)