International development minister Anneliese Dodds has quit over Sir Keir Starmer’s pledge to slash the aid budget to pay for higher defence spending.

Ms Dodds warned that pulling back from development would bolster Russia and encourage China to rewrite global rules on the international rule-based order.

In a scathing resignation letter she told Sir Keir: “Ultimately, these cuts will remove food and healthcare from desperate people.”

And she said the Prime Minister would find it “impossible” to deliver on his commitment to maintain development spending in Gaza, Sudan and Ukraine with the reduced budget.

Ms Dodds, who attended Cabinet and was also an equalities minister, said she backed Sir Keir’s decision to increase defence spending as the postwar consensus had “come crashing down” after Russia’s invasion of Ukraine.

She said she recognised there were “not easy paths” to doing so, and had been prepared for some cuts to the aid budget to help pay for the plan to increase military spending to 2.5 per cent of GDP by 2027 – and an ambition to hit three per cent in the next parliament.

But she said she believed the three per cent ambition “may only be the start” given the global picture, and urged the Government to look at other ways of raising the money other than through cutting departmental budgets, including looking again at borrowing rules and taxation.

But Sir Keir received backing from an unexpected source when Conservative leader Kemi Badenoch said the Prime Minister was ” absolutely right”.

Responding to the letter from Ms Dodds, the Tory leader said: “I disagree with the PM on many things BUT on reducing the foreign aid budget to fund UK defence? He’s absolutely right. He may not be able to convince the ministers in his own cabinet, but on this subject, I will back him. National interest always comes first.”

The shock resignation comes just a day after Sir Keir enjoyed one of the most successful days of his premiership following his meeting with Donald Trump in the White House.

Ms Dodds, who was Sir Keir’s first shadow chancellor after he became Labour leader, revealed she had only been told about the cut to her budget on Monday.

She said she decided to delay her resignation so it did not overshadow the Prime Minister’s crucial trip to Washington.

In her letter to the Prime Minister, she wrote: “Undoubtedly the postwar global order has come crashing down. I believe that we must increase spending on defence as a result; and know that there are no easy paths to doing so.

“I stood ready to work with you to deliver that increased spending, knowing some might well have had to come from overseas development assistance. I also expected we would collectively discuss our fiscal rules and approach to taxation, as other nations are doing.

“Even 3 per cent may only be the start, and it will be impossible to raise the substantial resources needed just through tactical cuts to public spending. These are unprecedented times, when strategic decisions for the sake of our country’s security cannot be ducked.”

She said it would be “impossible” to maintain priorities such as Gaza and Ukraine “given the depth of the cut”.

“The effect will be far greater than presented, even if assumptions made about reducing asylum costs hold true,” she wrote.

And she warned of the potential impacts on Britain’s national security and global influence as hostile nations moved into the breach.

“The cut will also likely lead to a UK pullout from numerous African, Caribbean and western Balkan nations at a time when Russia has been aggressively increasing its global presence,” she said.

“All this while China is seeking to rewrite global rules, and when the climate crisis is the biggest security threat of them all.”

Ms Dodds said she had made up her mind to quit the role on the day she learned about cuts, but had held off until after Sir Keir had returned from Washington.

She wrote: “It was imperative that you had a united Cabinet behind you as you set off for Washington. Your determination to pursue peace through strength for Ukraine is one I share.

“It is for that reason that I am only writing to you now that your meeting with President Trump is over, and four days after you informed me of your decision to cut overseas development assistance to 0.3 per cent of gross national income.”

She concluded: “Ultimately, these cuts will remove food and healthcare from desperate people – deeply harming the UK’s reputation. I know you have been clear that you are not ideologically opposed to international development. But the reality is that this decision is already being portrayed as following in President Trump’s slipstream of cuts to USAid.”

It means Sir Keir has so far lost four members of his Government during his first year as Prime Minister. Other resignations include Louise Haigh who quit as transport secretary, Tulip Siddiq who resigned as economic secretary to the Treasury and Andrew Gwynne, who was sacked from job as under-secretary of state for public health and prevention for comments in a WhatsApp group.

Conservative Former foreign office minister Andrew Mitchell said Anneliese Dodds had “done the right thing” by resigning as international development minister.

The Tory MP for Sutton Coldfield said: “Anneliese has done the right thing.

“Labour’s disgraceful and cynical actions demean the Labour Party’s reputation as they balance the books on the backs of the poorest people in the world. Shame on them and kudos to a politician of decency and principle.”

Monica Harding MP, Liberal Democrat International Affairs Spokesperson, said: “Anneliese Dodds has done the right thing. The Government’s position on the international aid cut is unsustainable.

“Increasing defence spending to 2.5% is the right thing to do as the global threats we face intensify. But doing so by cutting the international aid budget is like robbing Peter to pay Paul. The Government hasn’t even carried out an impact assessment.

“Diplomacy, development and defence are not competing priorities – they are complementary. Where we withdraw our aid, it’s Russia and China who will fill the vacuum.”