The British economy gre far more slowly than expected in the first quarter of 2015, official data showed Tuesday, delivering a blow to the government just nine days before a general election.

Gross domestic product expanded by 0.3 percent between January and March compared with GDP growth of 0.6 percent in the final quarter of 2014, the Office for National Statistics (ONS) said in an initial estimate.

Analysts' consensus had been for a slowdown in growth to only 0.5 percent in the first quarter, according to Bloomberg News.

GDP, the main indicator of economic growth, is the last major piece of data on the British economy before Britain votes in a knife-edge general election on May 7.

The ONS said that while output increased in services by 0.5 percent in the first quarter, the other three main industrial groupings in the economy decreased, with construction falling by 1.6 percent, production by 0.1 percent and agriculture by 0.2 percent.