The pace of gross domestic product (GDP) growth in the first quarter was half the 0.6 per cent rate seen in the final quarter of 2014, a pre-election setback for Coalition parties.
It was the weakest quarterly growth since the end of 2012. The data comes just nine days before the general election as politicians vie to demonstrate their competence in running the economy.
The preliminary estimate published by the Office for National Statistics (ONS) showed the dominant services sector grew at its slowest pace in almost two years.
Meanwhile, the construction sector shrank for the second quarter in a row – the first time this has happened since 2012.
Industrial production also shrank slightly, squeezed by a decline in North Sea output amid lower oil and gas prices, though within production manufacturing edged up.
ONS chief economist Joe Grice said: “The economy expanded a little more slowly in the first quarter of 2015 than we’ve seen in the past two years and that’s largely due to the services sector, where growth has eased to 0.5 per cent.
“In addition, there has been a further fall in construction output that itself takes around 0.1 per cent off the GDP growth rate. But, as always, we warn against reading too much into one quarter’s figures.”
Chancellor George Osborne tweeted that today’s figures show the “future of the economy is on the ballot paper”.
He added: “We should stick to the plan that’s delivering a brighter more secure future.”
But Howard Archer, chief UK and European economist at IHS Global Insight, said: “Given that the Conservatives and Liberal Democrats are hoping that many undecided voters will ultimately decide to vote for them due to their management of the economy, this marked slowdown in growth is particularly unwelcome news coming just over a week before the general election.”