Keir Starmer's aides have been told to block Andy Burnham from becoming the Prime Minister's successor 'at any cost', it has been claimed.

The Greater Manchester mayor was prevented from being Labour's candidate in the Gorton and Denton by-election in February by Sir Keir and his allies.

But Mr Burnham is widely expected to make another attempt to return to the House of Commons, from where he could launch a leadership challenge against Sir Keir.

The PM's grip on power has been weakened further in recent weeks by fresh revelations in the Peter Mandelson scandal.

And Sir Keir's team are alert to the threat of a potential coup following next month's local elections, in which Labour is set to perform dismally.

A veteran Labour MP on Monday opened the door to giving up his safe seat to help Mr Burnham return to Parliament.

But it has been reported that Sir Keir's allies have been ordered to mount a 'stop Andy' campaign.

The PM's aides are said to have been instructed in 'no uncertain terms' to ensure Mr Burnham does not succeed Sir Keir as Labour leader.

A senior party source told The Times: 'They have been told to stop Andy being Keir's successor in no uncertain terms, at any cost.'

It comes after allies of Angela Rayner, the former deputy PM, denied claims she had agreed a pact with Mr Burnham to support him for the leadership.

He is said to offered Ms Rayner 'any Cabinet job she wants' - plus a promise to 'stand aside' so she can follow him into No10 - if she backs his pitch for the top job.

Such a move would echo the 'Granita Pact', sealed by Tony Blair and Gordon Brown in 1994, before they went on to lead Labour for a combined 16 years.

Mr Burnham is said to have outlined the plan in secret talks at Ms Rayner's Greater Manchester constituency home earlier this month.

But the pitch has seemingly been dismissed out of hand by Ms Rayner, with allies saying she can win on her own and has no interest in being a junior partner.

Peter Dowd, who has been Labour MP for Bootle since 2015, on Monday refused to deny reports that he was prepared to stand down for Mr Burnham.

It has been claimed that he is one of three Labour MPs under pressure to give uyp their seats to allow the Greater Manchester mayor to return to Westminster. 

Asked directly by The Telegraph whether he was prepared to give up his Merseyside seat for Mr Burnham, Mr Dowd said: 'I'd rather not comment.' 

Meanwhile, Green leader Zack Polanski did not rule out forming a future coalition government with Labour under the leadership of either Mr Burnham or Ms Rayner.

'It's no secret that Andy Burnham and Angela Rayner would be much closer to my politics than Keir Starmer,' he told Sky News.

The self-described 'eco-populist' has previously said he would not be willing to work with Labour while Sir Keir remains the party's leader.