Keir Starmer has hit back at critics over his decision to slash billions of pounds from international aid.
The PM was last week rocked by the resignation of Labour minister Anneliese Dodds, who said it would have a huge impact on the world's poorest people. Mr Starmer cut the budget in order to ramp up spending on defence, vowing to commit 2.5% of gross domestic product (GDP) by 2027.
Humanitarian campaigners warn the impact of the cut - worth around £6billion a year - will be "devastating". On Friday Ms Dodds quit as international development minister saying the UK's reputation would be hit by removing funding to support "desperate people".
Confronted about her resignation by the BBC's Laura Kuenssberg, the PM said: "She's an incredibly committed politician of the highest integrity, and I respect her hugely.
"On this, making the decision to cut overseas aid and development is not something I wanted to do, but when peace in Europe is in issue, when the security and defence of the country is an issue, then difficult choices have to be made."
He continued: "What I'm going to do now is make sure that we go through line-by-line what spending we have on aid, and make sure we've got our priorities right, because we've got to focus on Gaza, Sudan, and Ukraine, of course.
"But I also want to work in a more innovative way to make sure we've got more development."
Ms Dodds quit over the decision to cut overseas development aid to 0.3% of GNI (gross national income) - down from 0.5%.
She warned; "Ultimately, these cuts will remove food and healthcare from desperate people - deeply harming the UK's reputation."
Ms Dodds, who attended cabinet in her ministerial role, also told Mr Starmer that the move could empower tyrant Vladimir Putin further. She wrote: "The cut will also likely lead to a UK pull-out from numerous African, Caribbean and Western Balkan nations - at a time when Russia has been aggressively increasing its global presence."
Dan Paskins, an executive director at Save the Children UK said: “Slashing the aid budget to a historic low is not in the UK’s national interest and the cuts must be reversed immediately. Thousands of children will suffer worldwide without the assistance of UK aid.
"It was a small reassurance to hear Prime Minister Keir Starmer say today he will focus on Gaza, Sudan, and Ukraine specifically where there is currently urgent need, but the only way to ensure our national security long term is to increase investment in our aid spending, not cut it."
He went on: “The budget reduction will mean fewer vaccinations, fewer children able to go to school and more children going hungry. This is devastating."
Labour minister Nick Thomas-Symonds claimed the move was "squarely in the Labour tradition" in spite of the growing backlash.
Told the Government had "taken money from the poor in the world " by Sky News host Sir Trevor Phillips, he said: "This decision has not been an easy decision, of course it hasn't. But it is the right one for the security of our country."
He said: "I think that the necessity of the moment requires that we significantly increase our hard power, significantly increase military spending. I think this is a once-in-a-generation moment. And I joined a government that said that it would put national security first."