Aid money must not be diverted to defence projects, Labour has said following reports Priti Patel could use the development budget to fight terrorism.
Shadow international development secretary Kate Osamor said aid money should not become a "slush fund" to bail out the cash-strapped defence budget.
She claimed International Development Secretary Ms Patel had made it clear the Government now had no plans to deliver the UK's commitment to spending 0.7% of national income on overseas aid.
Ms Osamor's comments came after The Mail On Sunday reported that Ms Patel planned to cut spending on traditional aid projects and instead focus the money on boosting national security.
The newspaper said that Ms Patel was reluctant to abandon the 0.7% commitment but would spend the money in a way which had a more direct benefit to the UK.
It quoted an MP familiar with her thinking as saying: "She knows people never swallowed (David) Cameron's line that these billions going abroad were in any way helping UK PLC.
"From now on, the watchwords are national security and the national interest. If those bells don't ring, the projects will be scrapped."
Ms Osamor said: "Priti Patel has made it clear that the Government now has no plans to deliver on the UK's 0.7% aid budget.
"The UK's commitment to international development must be just as important as international security and safety. The UK needs to remain at the forefront of offering stability, democracy and financial resources to the least developed countries.
"International aid should not be used as a slush fund to bail out the underfunding of defence. UK aid is vital in supporting those around the world most in need and any cuts in that support will have a devastating impact on the vulnerable.
"If it is the case that the Government has abandoned the UK's commitment to the UN sustainable development goals to end poverty it is an extremely worrying development that smacks of isolationism."