Major multinational aid funding may be cut unless it provides better value for money, International Development Secretary Priti Patel has said.
More than £4bn of UK aid goes to global organisations such as the World Bank.
In an interview in Kenya with BBC diplomatic correspondent James Landale, Ms Patel also said that she wanted to use the aid budget to help pave the way for trade deals.
She was speaking on her first visit to Africa since she was appointed.
Ms Patel witnessed what some of her department’s £12bn budget is supporting on the ground.
She saw humanitarian aid being delivered, via a payment card that gives Kenyan women £20 a month from the British taxpayer to buy the food they need to survive.
Spending better and wasting less
She said: "We have to make sure that our aid works in our national interest and also that it works for our taxpayers. Much more openness, much more transparency and much more accountability."
She is about to publish a review of the work of big multinational aid organisations that spend money on behalf of the UK, and said she would cut off funding if they did not meet new performance targets by spending better and wasting less.
"The government’s approach is focused on ensuring that we drive taxpayer value - so when it comes to multilateral organisations, focus on performance agreements," she said.
"If they are not performing then obviously we’ll look at the contributions that we give to them. We need to be challenging."
Trade deals and new allies
Ms Patel was referring to agencies such as the World Bank, the European Union and other smaller bodies. They spend 40% of the UK’s aid budget.
Our correspondent says Ms Patel also wants to use bilateral aid to secure new trade deals and make new allies in the World Trade Organization which the UK will need after Brexit.
Ms Patel said: "British soft power is exactly where DfID (the Department for International Development) and our aid and other relationships around the world come together to deliver in our national interest and deliver for Britain when it comes to free trade agreements but also life post-Brexit."