Mr Brown's finance minister Alistair Darling will on Monday unveil a package of tax cuts and extra public spending expected to total up to 20 billion pounds ($45.4 billion) in an attempt to keep Britons spending and stop the economy seizing up.
The centrepiece will be a temporary cut in sales tax paid on many goods, several newspapers reported on Sunday.
They said the tax, known as value added tax or VAT, could go down to 15 per cent from 17.5 per cent for one or two years, giving a pre-Christmas boost to consumers' spending power.
Britain, buffeted by the global financial crisis, is on the verge of recession, with house prices slumping, unemployment rising and manufacturing output shrinking.
The cash injection will be paid for with borrowing, which could send Britain's budget deficit ballooning to around 120 billion pounds in the next financial year.
Opposition Conservatives say the government's plan is unaffordable, risky and unlikely to work.
'Doing nothing is not an option,' Mr Brown said in excerpts of a speech he will give at a business conference on Monday. 'We need timely action now to prevent permanent damage.'
The package is a gamble for Mr Brown, whose handling of the financial crisis has lifted his flagging popularity ratings. His hopes of winning the next general election, due by mid-2010, may depend on the recession being relatively short and shallow.
Conservative lead
An opinion poll published in the Sunday Mirror showed the Conservatives with an 11-point lead over Mr Brown's Labour Party, contradicting a run of recent surveys which had seen Labour fighting back to within about three points of the Conservatives.
The upturn in Mr Brown's fortunes led to reports last week - dismissed by Mr Brown - that he might call an election in June.
Mr Darling, conceding that Britain was moving into recession, promised on Sunday that every household would get support now.
'Worried mortgage holders will get help and I shall do what I can to help those who lose their jobs. And I will state exactly how we intend to pay for the help we are providing now,' he wrote in the Sunday Mirror newspaper.
The Conservatives' Treasury spokesman Philip Hammond told BBC radio the Conservatives backed specific, funded tax cuts but opposed Mr Brown's plan for 'a give-away budget of tax cuts, funded by borrowing which has to be clawed back through higher taxes a year or two down the line.' -- THOMSON REUTERS