Britain will work with other countries to speed up the development of an HIV vaccine, Chancellor Gordon Brown said on World Aids Day.
Mr Blair said locally led programs are vital
He added Britain would buy up stocks to guarantee a market for vaccines being developed by researchers.
Earlier Prime Minister Tony Blair said dealing with problems in Africa, including HIV and Aids needed money and good leadership.
He said HIV/Aids would be one of the priorities of Britain's G8 presidency.
During the Queen's Speech debate, Mr Brown said: "For every year we bring forward the discovery of an Aids vaccine, we would save two million lives that would
otherwise be lost."
There are an estimated 25m people living with HIV in Africa.
Without a vaccine, it is estimated that 5-6 million people will be newly infected with HIV every year for the next 20 years - so more than 100 million people will be infected with HIV by 2025, on top of the 75 million who have contracted HIV since the early 1980s.
The government pledged that Africa, the environment and climate change would be priorities when Britain takes the helm of the G8 group of rich nations next year.
BBC world affairs correspondent Mike Wooldridge said the prime minister said it was important to realise that Africa is not "a continent without hope".
"Part of the problem is that I think people get fatigued and tired with looking at Africa because it all seems so hopeless," he said.
"It isn't. There are things that can be done and there are real success stories."
He said good leadership, both internationally and locally, were vital to stemming the spread of HIV and Aids.
"The thing that has worked in respect of combating Aids is when you've had a well-financed program, locally led, with accessible health and educational help for people there.
"The thing that is most frustrating of all is that we do know what works."
Mr Blair said doing more to help Africa help itself would reduce a potential threat to the world.
Aids Day campaigns aim to raise awareness around the world
"If we create a continent of alienation, desperate poverty, war and disease we know enough about the modern world to know there are issues there.
"But it is also a moral question. One in six African children is dying. It is a terrible situation - and it is preventable."