Keir Starmer again refused to give any timetable for publishing the crucial defence plan today amid bitter Cabinet infighting.

Sir Keir would only say the 10-year investment plan would be released ‘as soon as possible’ as he was challenged by Kemi Badenoch at PMQs.

He said he ‘respected’ ex-Nato chief Lord Robertson – the latest Labour grandee to demand more funding – but disagreed with his views.  

The bitter clashes came amid claims Rachel Reeves has been resisting pressure to fill an estimated £28billion black hole in budgets over the next four years. 

Instead she is said to be insisting that the Treasury can only afford £10billion of extra funding, leaving the Ministry of Defence scrambling to find cuts and efficiencies.

The wrangling comes despite Lord Robertson adding his voice to warnings that Britain has been left in ‘peril’ by the lack of investment in the armed forces.

After Ms Reeves scrapped the two-child benefit cap and dropped efforts to curb spiralling handouts, the peer said the ‘cold reality of today’s dangerous world is that we cannot defend Britain with an ever-expanding welfare budget’.

Two other Labour former defence secretaries have criticised the Government. 

Geoff Hoon said that Lord Robertson’s public intervention showed something had gone ‘seriously wrong’. 

Lord Hutton said the issue was the ‘defining moment’ in Sir Keir’s premiership, saying he has ‘a very, very short period of time to start putting this right’.

Keir Starmer would only say the 10-year investment plan would be released ‘as soon as possible’ as he was challenged by Kemi Badenoch at PMQs

Rachel Reeves has been resisting pressure to fill an estimated £28billion black hole in budgets over the next four years

Defence Secretary John Healey is believed to be pushing for more than £10billion extra over the next four years, pointing to the increasing demands on the military from tensions with Russia and chaos in the Middle East

Defence Secretary John Healey is believed to be pushing for more than £10billion extra over the next four years, pointing to the increasing demands on the military from tensions with Russia and chaos in the Middle East.  

Ms Reeves has already imposed more than £75billion a year worth of tax rises on Brits.

But that has been eaten up by the slowing economy, more benefits, big public sector pay awards and higher debt interest costs. 

Labour’s former deputy leader Harriet Harman has suggested means-testing the pension triple lock, telling the BBC: ‘If you’re strapped for cash and need to divert some money to defence, that is one place to be looking.’

It has emerged that the Treasury is pushing the Ministry of Defence to find £3.5billion in cuts this year – almost the exact cost of scrapping the two-child benefits cap.

Last year, Mr Healey said Labour would publish the ten-year Defence Investment Plan by the Autumn.

Speaking in the Commons today, Sir Keir said: ‘Let me start by saying I respect Lord Robertson and I thank him again for carrying out the strategic (defence) review.

‘My responsibility is to keep the British people safe, and that is a duty I take seriously. That is why I don’t agree with his comments

‘Last February, that was seven months after taking office, I took the decision to increase defence spending from 2.3% to 2.6%, paid for by my difficult decision on overseas aid.

‘Last June, at the Nato summit, I committed to raising core defence spending to 3.5% Last November, the budget committed record funding to defence. I reaffirm those commitments now.

‘The strategic defence review, is a 10 year blueprint for national security. The defence investment plan will put that into effect. It will be published as soon as possible.’

The Chancellor has also signalled she is unwilling to look again at future defence spending until a planned comprehensive spending review in the summer of 2027.

The Government has committed to spend 2.5 per cent of GDP on defence by 2027, with a vague ‘ambition’ to increase that to 3 per cent in the next Parliament.

There is a Nato-agreed target of hitting 3.5 per cent by 2035.

Lord Robertson, who wrote the Government’s strategic defence review last year, accused Ms Reeves of blocking funding for the Armed Forces and urged ministers to free up cash by slashing the bloated benefits budget.

‘Britain’s welfare budget is now five times the amount we spend on defence. So I ask, are we certain that this is the right priority – jeopardising people’s future safety and security, while maintaining an increasingly unsustainable welfare bill?’

Lord Hutton, who served as both defence and work and pensions secretary in the last Labour government, told Times Radio that Sir Keir must ‘get a grip on the rising welfare budget’. 

He warned that there is ‘no real sign’ the Labour administration has ‘any agenda for correcting the very steep rise in welfare payments’.

Touring broadcast studios this morning, Treasury Chief Secretary James Murray said he had ‘a lot of respect for Lord Robertson’. 

‘But I think on the question of welfare and defence spending, it’s not a zero-sum game,’ he added. 

‘As I said earlier, we’ve decided to have the biggest sustained increase in defence investments since the Cold War. 

‘I’ve set out all of the figures around that already. At the same time, we’ve begun our work to reform the welfare system, changing universal credit, reducing fraud and error, reforming motability.’ 

He added: ‘What’s important for me is to point out that whilst we are having these really important discussions around the defence investment plan and how that money is spent, we are already investing a billion pounds in new helicopters.’

A Government spokeswoman said: ‘We have delivered the largest sustained increase in defence spending since the Cold War – taking the total investment to more than £270billion across this Parliament.

‘We are finalising our Defence Investment Plan that we will publish as soon as possible, rebuilding British industry to make defence an engine for growth and doubling down on our own commitment to NATO.’