The worst performance for the UK economy in more than two years delivered a pre-poll blow to George Osborne as growth slowed sharply to just 0.3% in the first three months of the year.
The shock disappointment in the Office for National Statistics’ initial estimate comes just nine days before the closest general election in four decades.
Flagging construction activity was responsible for dragging down the economy’s overall growth rate, sliding 1.6% in the first quarter.
The expansion of services firms - according for more than three-quarters of output - also cooled to 0.5%, pushed down by the weakest growth in business services and finance since the end of 2010. That left growth overall at its weakest since late 2012.
Economists struggled to explain the figures against a backdrop of record low inflation of 0% and record low interest rates.
Oxford Economics senior economist Martin Beck said: “Given the signs from elsewhere in the economy and the healthy survey data, I wouldn’t put too much weight on these early numbers. They look ripe for revision.”
But the pound lost ground against the euro and the dollar.
The annual pace of growth also slowed, with the UK economy now 2.4% bigger than it was in the first quarter of last year.
Experts said the UK’s economy would need to pick up speed in the quarters ahead to meet the Office for Budget Responsibility’s 2.5% growth target this year.
Royal Bank of Scotland UK economist Ross Walker said: “The key question remains whether the slowing in growth – GDP growth has been decelerating from a recent peak of 0.9% in the first quarter of 2014 – will persist/settle at these sub-trend rates or, alternatively, whether the economy will stage a more sprightly pick-up (as the Bank of England and most City forecasters expect).
“We remain anchored at the pessimistic end of the forecasting spectrum and now cut our 2015 full-year GDP forecast to 2.2% from 2.4%. The latest consensus figure stands at 2.6% with the BoE at 2.9%.”
The preliminary reading of GDP is largely an estimate by Britain’s statisticians with more half of the data yet to be gathered, and the figures are often revised.
