Labour's bitter leadership battle is set to grow even more rancorous amid claims ex-prime minister Tony Blair will ramp up his interventions this summer.

Sir Tony, who was Labour premier between 1997 and 2007, this week made an explosive entry into the party's infighting as MPs mull whether to ditch Keir Starmer.

In a 5,600-word essay, he accused his party of retreating into a Left-wing 'comfort zone' with no 'coherent plan' for transforming Britain.

Sir Tony urged Labour MPs to 'force people to say where they stand' if they do push for a leadership contest, with Andy Burnham and Wes Streeting as likely candidates.

One of the ex-PM's allies claimed Sir Tony's intervention was 'the beginning, not the end' of his efforts to influence the party's future direction.

They told The Times that Mr Burnham's claim that '40 years of neoliberalism' had put Britain on the 'wrong path' had 'put fire in Tony's belly'.

Amid concerns that Labour will drift further to the Left under a Mr Burnham premiership, Sir Tony said the party risked consigning the UK to 'relegation from the Premier League of nations'. He also criticised Mr Streeting's policy proposals.

But both Mr Burnham and Mr Streeting have hit back at the ex-PM's comments, with Mr Streeting - the former health secretary - taking a swipe at Sir Tony over his 2003 invasion of Iraq.

In an interview with The Observer, Mr Burnham said Sir Tony did not understand the economic factors driving support for parties like Reform UK and the Greens. 

'He doesn't mention inequality once,' Mr Burnham said.

'If you don't get how that's driving politics now, if you are not rooting your analysis in the fact that people are unable to live and that things that were taken for granted are no longer affordable, then you are not understanding what's going on.' 

Mr Streeting was criticised in Sir Tony's essay for his proposed wealth tax and call for Britain to rejoin the EU.

In an article for The Guardian, the ex-Cabinet minister argued the 'striking weakness at the heart of' Sir Tony's intervention was the lack of mention of inequality.

He also hit out at Sir Tony's suggestion that Sir Keir should have initially allowed Donald Trump to use British military bases for US strikes on Iran.

Mr Streeting wrote: 'Our alliance with the US remains indispensable and rooted in deep historical ties. But Atlanticism cannot mean automatic subservience.

'When US presidents flirt with authoritarian leaders, undermine international law or pursue reckless military adventurism, Britain must have the confidence to act independently.

'We learned at terrible cost in Iraq what happens when loyalty replaces judgment.'

Sir Keir on Thursday dismissed Sir Tony's criticisms of his Government's policies.

The PM told reporters on a visit to the Acton Works train depot in west London: 'I agree with him that we should be having a discussion about policy and ideas, and that's what generates politics, that's where the focus should be, so Tony is right about that.

'You won't be surprised to know that I don't agree with much of what Tony says about what the Government is doing.

'We can all argue about individual policies, but the real question is what's the change? What's the difference that is happening in a country that we inherited two years ago in a very poor place?'

Sir Keir added: 'My response to Tony is, yes, it's right to talk about policy, it's right to talk about ideas, that's where the debate should be.

'But actually no, I don't agree that the policy choices of this Government weren't the right policy choices given what we inherited, a very different situation in 2024 to 1997.

'And dealing with what we had to turn around, the policy choices, we're vindicated by them because those changes have happened.'