(Bloomberg News) The U.K. economy shrank in the first quarter as Britain slid into its first double-dip recession since the 1970s, forcing Prime Minister David Cameron to defend his spending cuts in Parliament.

Gross domestic product fell 0.2 percent from the fourth quarter of 2011, when it declined 0.3 percent, the Office for National Statistics said today in London. The median of 40 estimates in a Bloomberg News survey was for an increase of 0.1 percent. A technical recession is defined as two straight quarters of contraction.

As an anti-austerity backlash gains ground in Europe, Cameron described the data as "disappointing" and pledged to support growth without backtracking on the U.K.'s biggest fiscal squeeze since World War II. The Bank of England is in the final month of its latest round of economic stimulus and the drop in output comes as prospects dim in the euro region, Britain's biggest export market.

"This isn't supportive of the fiscal consolidation program, so the government is likely to be concerned about that," said Philip Rush, an economist at Nomura International in London. "The data were bad, and that supports the view that the Bank of England will do a final 25 billion pounds of quantitative easing in May."

Bank of England policy maker David Miles had signaled yesterday that today's result was possible, saying in an interview with Bloomberg News that a negative number "wouldn't be a great surprise."

U.K. 10-year gilts advanced immediately after the data were published before easing again. The yield rose 3 basis points to 2.123 percent as of 1:12 p.m. in London. The pound fell as much as 0.4 percent, then pared its decline to $1.6116.

Construction Slump

From a year earlier, the economy was unchanged in the first quarter. The median estimate in a Bloomberg survey of 31 economists was for 0.3 percent growth from a year earlier.

The quarterly drop in GDP was due to a 3 percent slump in construction, the most since the first quarter of 2009, and a 0.4 decline in industrial production. Manufacturing contracted 0.1 percent and services, the largest part of the economy, expanded by 0.1 percent, boosted by transport, storage and communication.

The data contrasts with a report today showing confidence among manufacturers rose to the highest level in two years this month. The Confederation of British Industry's quarterly gauge of factory optimism surged to 22 from minus 25 in January.