Britain has announced a new multi-billion-dollar immunization fund that could save the lives of millions of children in developing countries over the next decade.

The British health initiative aims to create a fund of $4 billion for immunizations in poor countries against diseases such as Hepatitis B, measles, polio and yellow fever.

British treasury chief Gordon Brown unveiled the plan ahead of a meeting of European Union finance ministers in Manchester. "This initiative will save five million children's lives between now and 2015. It's an example of international cooperation, so that we can have blanket vaccination of children in countries where only partial vaccination means that there are infectious diseases remaining," he said. "It will allow us to eliminate some of the worst dread diseases in the world."

Britain is pledging $130 million a year to the fund. France is putting up $100 million. Italy and Spain say they will contribute.

Mr. Brown says he hopes for more commitments soon from Australia, Canada, China, South Africa and Sweden.

The initiative also has the backing of the founder of the Microsoft Corporation, Bill Gates, whose foundation has pledged $750 million over the next 10 years.

The money for the vaccines will be raised from private capital markets, using the vaccination fund pledges as a guarantee for the loans.

Some critics say the finance scheme will end up trimming future aid budgets in developed countries because the loans will have to be repaid with interest.

But Mr. Brown says countries that benefit from the plan will need less aid in the future as they become wealthier, because their populations will be healthier and more productive.