"A contraction of at least 4% is much more likely," said Benjamin Williamson at the Centre for Economic and Business Research.
"Our latest forecast is for a 4.5% contraction this year, making 2009 the steepest single year contraction in economic activity since the 5.1% fall in 1931."
The International Monetary Funds predicted a 4.1% decline for 2009.
Chief Secretary to the Treasury Yvette Cooper said the government stood by its forecasts.
"We believe the economy will start to recover towards the end of this year," she told the BBC.
But Conservative leader David Cameron said the figures showed the government had a wildly optimistic view of the state of the UK economy:
"The chancellor gave a set of forecasts in the Budget," he said. "Everyone said they were over optimistic, and already, just a few days later, the next lot of official figures coming out shows that he's been over optimistic, shows that what the government's been doing hasn't been working."
James Knightley, an economist at ING Bank, said: "Today's GDP report does again highlight how optimistic Chancellor Darling was in his budget assumptions."
Alistair Darling had also predicted that GDP in the first three months of the year would be at a similar level to that seen in the previous quarter.
The ONS cautioned that the GDP figure was only its preliminary estimate and could be revised.
There was some better news for the economy in the latest retail sales figures.
Retail sales unexpectedly rose 0.3% in March, making them 1.5% above the level seen in March 2008.
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