John Healey has quit as defence secretary in a fresh blow to Sir Keir Starmer amid a row over defence spending. In a letter to the Prime Minister, he said he was left with “no other option” after disagreement over the delayed Defence Investment Plan (Dip).

He said: "We came into government recognising Britain faced a new era of threat which demanded a new era for defence."

He added: "Since then, you have been unable, and the Treasury has been unwilling, to commit the resources that the nation needs to defend the country at this time of rising threats."

Mr Healey said he had received a financial settlement for the Dip on Monday afternoon which “falls well short of what is required”, with extra support coming after 2030 when the “imperative to speed up readiness to fight is in the first two years”.

He said: “After explaining to you that I would not be able to accept a Dip settlement that does not give our forces the resources they need, I am now left with no other option than to submit my resignation as your defence secretary.”

The plan is due to be published ahead of the Nato summit in Turkey, which begins on July 7.

It was originally slated for publication last autumn but has been repeatedly delayed.

It comes after the PM yesterday refused to rule out tax hikes to fund defence spending.

He was pressed by Conservative leader Kemi Badenoch at Prime Minister’s Questions on whether taxpayers should expect an increase, but declined to respond directly.

In the Commons, Mrs Badenoch said: “There is still no defence investment plan.

“He is the Prime Minister now, at least I think he is – should I be calling Andy Burnham instead to ask these questions?

“He is the Prime Minister, and the reason that he’s dithering is because he doesn’t know where the money is coming from.

“The military is waiting, the bond markets are watching.

“He has only three options: cutting spending, more borrowing, or higher taxes.

“We know that the Chancellor wants to put up tax to pay for it.

“Will the Prime Minister rule out raising taxes?”

Sir Keir pointed to the Conservatives’ record in office, accusing them of causing “damage to the armed forces”.

He added: “When they left office, 47 out of 49 major defence contracts were delayed or over budget.

“That is what we are fixing. You can’t just scrub away and forget.

“I know they want to forget the last 14 years in power, so do the British public. That’s why they’re sitting over there.”