RIVAL candidates launched a desperate bid yesterday to snatch the Labour leadership away from frontrunner Jeremy Corbyn.

Andy Burnham, Yvette Cooper and Liz Kendall wrote a joint letter to party bigwigs that the contest did not have “a level playing field.”

They alleged that Mr Corbyn’s massive support from the labour movement put him at an unfair advantage, as unions know which of their members have signed up as affiliates.

The trio claim that they will be hindered by having to wait for contact details from the party while the unions can get cracking straight away.

“We are concerned we will only receive accurate lists in around 10 days’ time, which hinders each campaign’s effort,” their letter states.

The letter, reportedly instigated by Mr Burnham, was issued just hours after the deadline passed for new members and supporters to sign up for a vote in the contest.

For the first time non-members have been given the chance to vote by paying £3 to become supporters.

Labour says that 299,755 members as well as 189,703 affiliated and 121,295 registered supporters will be able to vote.

Just a tiny proportion of applications have been rejected — a total of about 1,200. Those include film director Ken Loach and comedian Mark Steel, turned away because they have supported other parties.

Four MPs called for the contest to be suspended yesterday, but Diane Abbott MP branded their remarks a “silly” attempt to stop Mr Corbyn.

“People are only complaining about the system now because they’re frightened their candidate will lose,” she told BBC News.

“They try smear Jeremy by saying he’s some militant extremist, but actually a lot of the things he’s talking about are very popular with ordinary people.”