More people are out of work in a third of constituencies across Britain than when the Conservatives left power, new figures revealed yesterday.

The striking statistic emerged as the Government braces itself for unemployment to pass two million this week. An analysis of unemployment in parliamentary seats shows that the problem is cutting deep into all areas of the country. The highest rises are in the South and Midlands, in many Tory seats and Labour marginals, underscoring the battle facing Gordon Brown to win the next election.

Unsurprisingly, major manufacturing centres in the Midlands have seen dramatic rises in the past 12 years. But sharp increases have also taken place in Tory areas. Wokingham in Berkshire has seen a 61 per cent rise in jobless since May 1997, while it has risen 60 per cent in South Holland and the Deepings in Lincolnshire. Labour marginal seats include Rossendale and Darwen, with a 46 per cent rise, Swindon North, up 44 per cent, and Corby, up 37 per cent.

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Last month it emerged that unemployment for the last quarter of 2008 reached 1.97 million, an increase of 148,000. Since January, tens of thousands of people have been laid off, suggesting the total will surpass two million, the highest for 12 years, when the Office of National Statistics publishes unemployment data on Wednesday.

Last week Work and Pensions Secretary James Purnell promised help for jobless white-collar workers. But the Tories claimed that last year one job centre was closed every week. Theresa May, the shadow Work and Pensions Secretary, said: "Labour's failure to tackle the skills gap has left too many people ill-prepared for the recession."