Gordon Brown's Budgets should be subject to an independent audit, the Liberal Democrats have said.
The call came after figures revealed higher-than-expected public debt just two weeks after the chancellor addressed the Commons.
At the end of March, public sector net borrowing reached £25.2 billion said the Office for National Statistics, compared to Brown's prediction of £24 billion.
The statistics cast doubt on estimates that borrowing would total £27 billion in this financial year, dropping to £24 billion in 2004/05.
"Today's borrowing figures, which are 18 per cent worse than predicted in the Budget only two weeks ago, reinforce the case for an independent audit of the chancellor's Budget," said Lib Dem Treasury spokesman Matthew Taylor.
He called on the chancellor to "restore his reputation by acting to ensure his Budget is believed".
"Without an independent audit and on current evidence, how can Britain believe your Budget predictions Mr Brown?" he asked.
The Conservatives also criticised the chancellor's failure to predict borrowing levels.
"The chancellor has already had to downgrade his forecasts twice in less than five months. With independent economists being more cautious than the chancellor about prospects for the coming years, these figures raise further questions about Gordon Brown's credibility," said Mark Prisk, shadow financial secretary.
The news came as the minutes from the last meeting of the Bank of England's monetary policy committee revealed that two members voted for a further reduction in interest rates.
Christopher Allsop and Marian Bell supported a quarter per cent cut as Britain's economy slowed.
The other seven committee members favoured the Bank of England's "wait and see" approach.
The report highlighted the importance of May's meeting. By then the impact of changes in the Budget will have been felt and a series of economic forecasts will be available.
"The war in Iraq had increased the difficulty in the interpreting survey responses, probably making them unduly pessimistic but to an unknown extent," the minutes said.
"It was difficult to know what weight to put on survey data at the current conjuncture because of the war in Iraq, but, arguably, it was unlikely that the downturn in indicators was all war-related."
