"The people of this country have fought too hard to get Britain on the road to recovery to allow anybody to take us back on the road to recession," Brown said in a statement previewing his campaign themes.

The opposition Conservative party, led by David Cameron, have said that they would cut the deficit faster than Labour but have now promised to exempt most workers from a rise in payroll tax that Labour plans from 2011.

That has won approval from the party's traditional business supporters.

"We're fighting this election for the great ignored. Young, old, rich, poor, black, white, gay, straight," Cameron said in a statement, showing how he has tried to make his party more inclusive.

Expenses scandal

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Gordon Brown compares UK economy to foot injury of English football striker

The outgoing parliament, which has served a full five years, has been tarnished by a high-profile scandal over politicians' expenses.

As many as 150 MPs are stepping down, many with reputations harmed by the scandal.

Due to scandal, some analysts expect fringe parties and independent candidates to pick up extra votes at the polls.

The Conservatives lead Labour in opinion polls but the gap has been narrowing.

A poll in Tuesday's Guardian newspaper showed Labour only four points behind the Conservatives, putting it on course to remain the largest party but without an overall majority.

Support for the Conservatives is unevenly distributed in Britain's 650 parliamentary constituencies, which means that Labour can win the most seats even if it does not capture the largest share of the vote nationally.

An inconclusive election result is rare in Britain and may rattle financial markets, which want a clear outcome and the promise of meaningful action to tackle a budget deficit running at almost 12 per cent of GDP.

Failure by either of the main parties to win a majority could hand a pivotal role to the smaller opposition Liberal Democrats, who will be trying to maintain a bloc of around 60 MPs in parliament.