Standing outside his Downing Street residence with his cabinet arrayed behind him, Mr Brown confirmed the May 6 election date, just a month before the last possible time for the vote.

"It's probably the least well-kept secret of recent years but the queen has kindly agreed to the dissolution of parliament and a general election will take place on May 6," Mr Brown said, starting his bid to extend his Labour Party's 13-year grip on power.

The opposition Conservatives lead centre-left Labour in opinion polls, but the outcome is far from certain as public support for both main parties remains volatile and the opposition faces a big challenge in securing power.

Opinion polls point to a hung parliament, one in which no party has an overall majority, because support for the center-right Conservatives is concentrated in fewer of the 650 parliamentary constituencies.

Reuters