Britain threw down the gauntlet to donors o­n Monday by announcing that it would commit £1bn to replenish the Global Fund to Fight Aids, Tuberculosis and Malariaon condition that other countries agreed to follow suit. The "all or nothing" pledge, intended to push other donors, was made at the UN general assembly. The money would be released over three years. In April, the Global Fund said it would need $15bn (£9.3bn) in replenishment funds for the 2014-16 period. The Department for International Development (DfID) said the first tranche of money would be available next year. Britain is due to meet its previous £1bn commitment for 2008-2015 a year early. DfID said the money would support antiretroviral treatment for 750,000 people living with HIV, provide an extra 32 million insecticide treated nets to prevent malaria and TB treatment for more than 1 million more people. Justine Greening, the UK's international development secretary, told a lunchtime event organised by the UN Foundation that the Global Fund "really works", which is why it was important to continue to support it. Britain is the fund's third largest donor, behind the US and France. "By 2015 we will have halved the mortality rate for TB since 1990," she said. "We have the potential to ensure this is the first generation that could be Aids free. So we are announcing a pledge of £1bn to the Global Fund under full replenishment of $15bn ... We can't do it all o­n our own, but if we all pitch together then we have a really good chance to put ourselves in shooting distance of some incredible results o­n HIV, TB and malaria."

Greening's announcement follows comments made during an evidence session (pdf) held by the international development committee in July that the UK could be seen as a soft touch for funding organisations like the Global Fund. Jeremy Lefroy, the Conservative MP for Stafford, said at the time: "It seems to me that, because these organisations see DfID's budget as, indeed, increasing this year and then stable, it is often the country that they are coming to almost first for that. I see that as a real problem. Do you think DfID should be much tougher o­n them and say, 'We will not increase unless we see other countries increasing'?"

The Global Fund, set up in 2002 as a public-private partnership to tackle the three major diseases that feature in millennium development goal number six, has recently been hit by accusations of corruption and mismanagement by some countries that received money from the body, providing a welcome excuse for some donors to cut funding during challenging economic times. The fund began a series of meetings with donors in April to kick off its fourth replenishment round, which is due to conclude with a pledging conference in December. The US president, Barack Obama, has promised $1.65bn in its 2014 budget, and, earlier this month, Sweden, Norway, Finland, Denmark and Iceland pledged $750m.

Britain's announcement has been widely welcomed. Nafsiah Mboi, chairman of the Global Fund board, said: "The UK gives us all an inspiring model of responsible global citizenship." Melinda Gates, from the Bill and Melinda Gates Foundation, said the UK was showing "incredible leadership" in making this commitment when other countries were "stepping back o­n aid". Alvaro Bermejo, executive director of the International HIV/Aids Alliance, said: "We applaud the UK government's announcement ... that they will give £1bn over the next three years if the Global Fund fourth replenishment goal of $15bn is met." But he added: "If the $15bn replenishment goal is met, the UK's contribution represents 10% of the total. What is less clear is what happens if that magic figure is not met. We will continue to work with the UK government to secure successful Global Fund replenishment." Stop Aids said: "The commitment from the UK throws down the gauntlet to other donor countries, like Germany, Australia and Japan, to dramatically increase their contributions so the Global Fund can secure the $15bn it says could tip the balance in the three epidemics. The ambition of the UK commitment matches that shown by the Obama administration, which has pledged $1.65bn for 2014 alone." The musician Elton John, a passionate Aids campaigner, said the UK had "done a great thing". "I commend the UK for this bold contribution to creating an Aids free future," he said. "By allocating exactly what was needed to the Global Fund, an amount I have been urging prime minister Cameron to commit, the determination of the UK government to defeating these diseases is beyond doubt. It has set an ambitious goal and an excellent standard that others must follow."

The Global Fund is estimated to have saved more than 8.7 million lives since it was set up; 4.2 million people are now receiving antiretroviral treatments, 9.7m new TB cases have been identified and treated, and 310m insecticide-treated nets have been distributed to protect against malaria.