Britain is to give £1bn over three years to The Global Fund to Fight Aids, Tuberculosis and Malaria, Justine Greening has announced at the United Nations in New York.

The international development secretary said the investment showed Britain was leading the way and claimed Britain's contribution would save a life every three minutes.

The Global Fund was created in 2002 as a public-private partnership to raise funds to significantly change the course of HIV/Aids, TB and malaria. The UK is the third largest donor, after the US and France.

Speaking at the UN general assembly meeting, Greening said: "Aids, TB and malaria are among the world's biggest killers despite being entirely preventable and treatable.

"The Global Fund has already helped save millions of lives but we must keep up the momentum if we are to beat these diseases for good.

"It is in all our interests to help people live longer, healthier, more productive lives so we all need to play our part in working towards a world free of HIV/Aids, malaria and TB."

Britain will become the fund's second largest contributor once the new raft of cash has been added.

The £1bn investment will fund lifesaving anti-retroviral therapy for 750,000 people living with HIV, 32 million more insecticide-treated nets to prevent the transmission of malaria and TB treatment for more than a million people.

Bono, co-founder of the ONE campaign, said: "The UK's pledge of up to a billion pounds for the fight against aids, TB and malaria means what once seemed impossible could now be within our grasp.

"Through this smart investment in one of the most effective disease-fighting funds in history, we could witness the defeat of these global killers in our lifetime.

"David Cameron and Justine Greening have given us a billion reasons to believe we can do it, but Britain's pledge will only be delivered if others step up too. Australia, Canada, Germany: your move."