Separate surveys this month showed that growth in services, manufacturing and construction accelerated in March. The British Chambers of Commerce said the GDP data is likely to be revised higher by the statistics office.

Surveys "have shown a more positive picture, and we believe these give a more accurate indication of the underlying trends," Chief Economist David Kern said in a statement today. "We think it is likely that the preliminary estimate will be revised upwards when more information is available."

The FTSE 100 index rose 0.1 percent today. Still, its 2.6 percent advance this year trails the 4.9 percent increase by Europe's Stoxx 600 Index.

Rising energy prices, government spending cuts and anemic wage growth are squeezing U.K. consumers, creating a drag on the recovery. Pay growth slowed to 1.1 percent in the three months through February, less than a third of the inflation rate. An extra public holiday in June to mark Queen Elizabeth II's 60 years on the throne may also depress economic output in the second quarter.

Britain, the first Group of Seven country to report output for the first quarter, was hit hard by the financial crisis that erupted in 2007 and GDP is still 4.3 percent below its pre- recession peak in early 2008. Only Japan and Italy are further behind among G-7 nations.

The last time Britain experienced a double-dip recession, defined as consecutive quarterly drops in GDP before the economy had recovered output lost in the previous recession, was 1975. That year, Labour Prime Minister Harold Wilson was in office and Margaret Thatcher was elected leader of the opposition Conservatives. U.K. Treasury forecasters and the International Monetary Fund predict the economy will grow 0.8 percent this year, the same as last year.

The data are "very, very disappointing," Cameron said in Parliament today, adding that "I don't seek to try and excuse them. There is no complacency at all." He pledged to stick to his deficit-cutting plans, saying "the solution to a debt crisis cannot be more debt."

'Very Tough'

Chancellor of the Exchequer George Osborne said the U.K.'s economic situation is "very tough" and the government shouldn't waver on its fiscal plans, which are aimed at eliminating most of the deficit by 2017.

"The one thing that would make the situation even worse would be to abandon our credible plan and deliberately add more borrowing and even more debt," he said in a statement.