The Organisation for Economic Co-Operation and Development (OECD) has called for "more explicit" spending cuts to tackle the UK's soaring debt.
Their report on the UK economy called for spending cuts and tax rises to address a deficit expected to hit 14% of GDP by 2010.
The body's criticism comes days after Bank of England Governor Mervyn King also demanded tougher goals from Chancellor Alistair Darling.
The report warned: "The schedule for rebalancing the budget after the current economic downturn abates should be more ambitious."
The UK is on course to borrow a record £175bn this year as tax receipts are hammered by the recession.
The OECD said value-for-money savings made in November's Pre-Budget Report and April's Budget did not go far enough.
"There should be more explicit targeting of programmes for expenditure cuts and temporary revenue raising measures should be considered to help expedite the rebalancing of the budget," it added.
The think tank thinks there will be a 90% rise in debt (as a proportion of national output) in 2010. It forecasts that the unemployment rate will near 10% next year.
It added that the Government could do "considerably more" to bring forward its programme of stabilising the public finances.
"Experience in other countries suggests that a focus on expenditure cuts, rather than revenue raising, is associated with more successful consolidations," it said.
It said that restoring the flow of lending to the economy was essential to a recovery - even if it meant nationalising more banks.