Gordon Brown has backed Yvette Cooper for the Labour leadership.

The former prime minister's office announced that he had given the shadow home secretary his first preference vote.

In a recent speech, Mr Brown had issued a thinly-veiled warning to the party not to pick left-winger Jeremy Corbyn but gave no endorsement to any of his three rivals.

But his office confirmed that he believed Ms Cooper was the best of the quartet to succeed Ed Miliband at the head of the Opposition - and had already cast his vote.

His second preference was Andy Burnham and third Liz Kendall, it said ahead of a weekend appearance at the Edinburgh Book Festival where he will set out his choice.

In his only previous intervention, a high-profile 50-minute speech in London he did not mention frontrunner Mr Corbyn be name - viewed as unelectable by many Labour MPs - but warned of the consequences of retreating to becoming a "party of protest".