The race to become British prime minister is wide open with experts predicting the UK is heading for another hung parliament and a coalition government.

Neck and neck poll rankings for Labour and the Conservatives, combined with surging support for the smaller parties, means the chance of an outright winner could be as low as 10 per cent.

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The countdown of the final 100 days to the country’s general election begins on Tuesday.

Academics running the 2015 UK Parliamentary Election Forecast website cautiously predict there will be no overall majority.

Their research – based on polling and previous election results – suggests there is only a 55 per cent chance of a coalition that can be formed from just two parties, opening up the very real possibility of a second election this year.

On current projections, they put Labour on 282 seats, the Conservatives on 281, SNP on 34, Liberal Democrats on 28 and UKIP on three.