Britain will donate an additional £814 million to vaccinate more than 80 million children against diseases like pneumonia and diarrhoea, David Cameron announced today. The Prime Minister said the money would help save 1.4 million lives in the developing world over the next five years. He was speaking at the Global Alliance for Vaccines and Immunisation (Gavi) conference in London, where world leaders, charities, private companies and philanthropists including Microsoft's Bill Gates were discussing how to generate the funds to ensure children receive protection against potentially fatal diseases. Mr Cameron told the conference: "Britain will play its full part. "In addition to our existing support for Gavi, we will provide £814 million of new funding up to 2015. "This will help vaccinate over 80 million children and save 1.4 million lives. "That is one child vaccinated every two seconds for five years. It is one child's life saved every two minutes. That is what the money that the British taxpayer is putting in will give." Mr Gates later told the conference that his Bill and Melinda Gates Foundation was pledging an additional one billion US dollars (£616 million) over the next five years to help the vaccination campaign. Mr Cameron acknowledged that the increased cash for vaccinations - part of the UK's goal of devoting 0.7% of national income to aid by 2013 - would be "controversial" at a time of cuts in spending on public services at home. He told the conference: "At a time when we are making spending cuts at home what we are doing today and the way we are protecting our aid budget is controversial. "Some people say we simply can't afford spending money on overseas aid right now, that we should get our own house in order before worrying about other people's problems. "Others see the point of helping other countries to develop, but they don't think aid works anyway, because corrupt dictators prevent it from reaching the people who really need it." But the Prime Minister rejected these arguments. "I think there is a strong moral case for keeping our promises to the world's poorest and helping them, even when we face challenges at home," he said. "When you make a promise to the poorest children in the world, you should keep it." Mr Cameron recalled watching the G8 summit at Gleneagles and the Live 8 pop concert in 2005 and thinking it was right that world leaders should make public pledges to help the poorest countries. "For me, it is a question of values," he said. "This is about saving lives. It was the right thing to promise. It was the right thing for Britain to do. And it is the right thing for this Government to honour that commitment." Some people were pressing him to put off aid commitments until after Britain's economy is back on an even keel, said Mr Cameron. But he insisted: "We can't afford to wait. How many minutes do we wait? Three children die every minute from pneumonia alone. Waiting is not the right thing to do. I don't think 0.7% of our gross national income is too high a price to pay for saving lives." And Mr Cameron said that there was a "strong practical" argument for aid, as it would help transform poor countries in Africa into trading partners for the UK, and would prevent the conditions which lead to mass migration, radicalisation and terrorism. "If we invest in countries before they get broken, we might not end up spending so much on dealing with the problems. Whether that's immigration or new threats to our national security," he said. Mr Cameron added: "I actually think that most people in our country want Britain to stand for something in the world, to be something in the world. "When I think about what makes me proud of our country, I think of our incredibly brave servicemen and women and of our capabilities as an economic and diplomatic power, but I also think of our sense of duty to help others. "That says something about this country and I think it's something we can be proud of." Acknowledging the problem of corruption, Mr Cameron said: "I totally get this argument. It's right to be angry when aid is badly spent. "Let me tell you: I'm not prepared to see a single penny of hard-earned money wasted on corrupt governments, or badly spent aid. "But the answer isn't to walk away from aid. It's to change the way we do development - so that we get real results and real value for money." Gavi's aim of raising £2.3 billion over the next five years will help protect at least a quarter of a billion children against killer diseases and save four million lives, said Mr Cameron. And he asked: "In this world, where countries are tackling deficits, and more than ever before the emphasis is quite rightly on getting value for money, what greater value for money can there possibly be?" British donations have already paid for the vaccination of 55 million children around the world since 2000, and even before today's pledge the UK was committed to giving £680 million between 2011 and 2015. Save the Children's new report, Vaccines For All, reveals that there are still around 24 million children - the world's poorest, and those most vulnerable to disease - who have no access to vaccines. This could be changed if Gavi gets the resources it needs, it says. Gavi's global immunisation programme includes the rollout of new vaccines against two of the biggest child killers - pneumonia and diarrhoea. Mr Gates was in optimistic mood, saying that a malaria vaccine could be just a few years away, while polio could follow smallpox in being eradicated thanks to the success of its vaccine. Vaccines are "magic", he added. "They are very inexpensive, they can protect you for your entire life, so diseases like smallpox that used to kill millions are completely gone because of the vaccine. It's the greatest thing that ever happened in human health. We need to get them out to people and invent some more." Jemima Khan, who is an ambassador for Unicef, praised the Government for "taking the lead" on the issue. "This conference is about saving four million extra lives by 2015. At the moment, one child every 20 seconds dies of a vaccine-preventable disease. That is still a very shocking figure given that we have the know-how, we have the expertise to do something about that," she told BBC Breakfast. And Jamie Drummond, executive director of the poverty campaigning organisation One, said: "David Cameron deserves immense praise for his pledge which will save a child's life every two minutes for the next five years. The Prime Minister and the British public have shown great moral leadership in the fight against disease and extreme poverty, as well as smart strategic thinking." Shadow international development secretary Harriet Harman said it was "unacceptable" that millions of children in the developing world die from illnesses which could be prevented by vaccinations which are taken for granted in the UK. "Today, there must be bold contributions from donors to ensure that Gavi has the resources it needs to save millions of children's lives and that the progress that has already been made does not stall," said Ms Harman. "The private sector must also play its part by supplying vaccines at the lowest possible prices." Oxfam senior policy adviser Max Lawson said: "David Cameron deserves real credit for tackling the aid critics head-on and committing much-needed funds to vaccinate children in poor countries. "The Prime Minister is right to say that vaccination is one of the most effective ways of improving health in poor countries. His Government has a key role to play in encouraging GAVI to further reduce the prices it pays to pharmaceutical companies to ensure that every penny goes towards protecting children from killer diseases."