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LONDON - Britain's Labour Government set off a political storm by acknowledging it had underestimated the number of foreign nationals who had come to work in the country in the past 10 years by 300,000.

The opposition Conservatives released a letter from Work and Pensions Secretary Peter Hain in which he apologised for having given them wrong information.

New analysis of labour-market data showed that instead of 800,000, "there are, in total, an extra 1.1 million foreign nationals in employment in the UK since 1997," Hain wrote.

Hain's department confirmed the upwards revision, which it said arose from "a more rigorous definition of foreign-national workers". Between 7 and 8 per cent of the 29.1 million people in work in Britain were foreign nationals, it said.

Immigration has become a hot political issue in Britain, with some people fearing that the fast pace of migration has put severe strain on housing, education and health services.

Conservative work and pensions spokesman Chris Grayling said the revision cast doubt on the Government's competence. "The fact that the Government did not know the true number of overseas workers who have come to the UK ... is profoundly worrying, and confirms fears that ministers have simply lost control of our systems for migrant workers."

Conservative leader David Cameron called for annual limits on migration to Britain from countries outside the EU.

- Reuters