Brown fires the starting gun

British Prime Minister Gordon Brown fired the starting gun on a month-long election race, setting May 6 as the date for voting in what could be the closest poll for a generation.

Announcing the widely-anticipated date after asking Queen Elizabeth to dissolve parliament, Brown warned that Britain's fragile economic recovery was at risk if the opposition Conservatives took power.

"Britain is on the road to recovery and nothing we do should put that recovery at risk," he told reporters.

"Our economy is now moving forward, but to withdraw millions of pounds from the economy would put recovery at risk."

Brown's confirmation of a date triggers a month of campaigning when his centre-left Labour will battle to claw back ground from David Cameron's centre-right Conservatives, who are ahead in opinion polls.

If Labour wins, it will be the party's fourth consecutive term in office and its first under Brown, who took over as leader from Tony Blair in 2007. The Tories are vying for their first victory since a surprise win in 1992.

In a contest likely to be dominated by the economy, Brown, 59, is contrasting his role in steering Britain to safety through the global financial crisis with what he says is 43-year-old Cameron's inexperience.

Cameron, who has extensively modernised the party of Margaret Thatcher since taking over as leader in 2005, called it "the most important general election for a generation".

"It is about the future of our economy, it's about the future of our society, it's about the future of our country," he said.

"It comes down to this. You don't have to put up with another five years of Gordon Brown." Whoever wins faces tackling a budget deficit of about £167-billion.

Cameron wants swift cuts to public services but Brown says these must be delayed to protect the fragile recovery.

Brown - whose campaign team has been inspired by Barack Obama's presidential election victory in the US - kicked off official campaigning at a supermarket in Kent, southeast England.

Cameron headed for a hospital in Birmingham, central England, while Nick Clegg of the centrist Liberal Democrats met young people in Watford, north of London.

Experts, bookmakers and opinion polls suggest the election will be the closest-run for a long time.

"This is going to be the most thrilling election Britain has had for more than 20 years," Fraser Nelson, editor of right-wing political magazine the Spectator, said.

"The two parties are far closer than anyone would have thought possible at this stage in the game."

Bookmakers Paddy Power make the Conservatives favourite to win the most seats in the vote but say the chances of a hung parliament - where no one party has an overall majority - are high.

The Conservatives held a double-digit opinion poll lead for much of Brown's premiership but that fell to single figures after January's announcement that Britain had emerged from its worst recession since World War Two.

A Daily Express/Opinium poll yesterday gave the Tories a 10-point lead while a Guardian/ICM poll put Labour four points behind Cameron's party.

The Conservatives need a huge swing of 6.9% to secure victory - equivalent to the landslide which swept Labour led by Blair to power in 1997.

Labour currently has 345 seats in the House of Commons, a working majority of 56, compared to the Conservatives' 193.

If, as polls suggest is possible, there is a hung parliament for the first time since 1974, the Liberal Democrats could play a key role in a minority or coalition government.