The British economy grew at the fastest rate for nine years in the second quarter, data confirmed today, one day after the the IMF praised the government's plans to cut the public deficit.
Gross domestic product expanded by 1.2 percent in the April-June period, the Office for National Statistics said in a statement.
That was the best performance since the first quarter of 2001 and was in line with expectations.
However, news of surging output comes amid growing concern that the economy faces a difficult future as spending cuts and tax hikes bite.
"The second-quarter growth pace is clearly unsustainable in the face of major headwinds, most notably including tight fiscal policy increasingly biting, persistent tight conditions, slowing global growth and pressurized consumers," said IHS Global Insight economist Howard Archer.
Britain's coalition government, which rose to power in May, is seeking to slash the public deficit mainly by severely slashing state spending.
Deep expenditure cuts are expected in a so-called comprehensive spending review that is due on October 20.
The International Monetary Fund on Monday backed the Conservative-Liberal Democrat government's deficit-slashing policy, describing the swift and aggressive measures as an "essential" weapon in reducing debt.
The IMF said Britain's economy "is on the mend" but nonetheless cut its 2011 growth forecast for the country to 2.0 percent from a previous estimate of 2.1 percent.
British finance minister George Osborne seized on the IMF report, saying it was a "very welcome endorsement" of his strategy.
"They have made it pretty clear that the deficit reduction plan that we have set out is essential for bringing about sustainability in our budget," he told the BBC on Monday.
"It reminds us that if we divert from the course the new government has set out then we really will be heading back into a disastrous period of economic instability for Britain."
In June, Osborne delivered a deficit-slashing emergency budget amid intense concern about soaring debt levels in Europe.
The coalition, led by Prime Minister David Cameron's Conservatives, inherited a record 154.7-billion-pound (240-billion-dollar) deficit from the previous Labour administration which it ousted at a recent general election.
The main opposition Labour party, looking to win back power under new leader Ed Miliband, says the coalition's deficit-reduction plan is far too quick and aggressive and risks plunging Britain back into recession.
On a downbeat note, the ONS added on Tuesday that the British economy shrank by more than previously thought last year, contracting by 5.0 percent in 2009 instead of the earlier estimate of 4.9 percent.
"Overall this release doesn't do much to alter the outlook," said Andrew Goodwin, Senior Economic Advisor to the Ernst & Young ITEM Club.
"Growth is likely to be much slower in the second half of the year, but we are still some way away from double-dip territory."