Microsoft chairman Bill Gates has donated $750m of his fortune to immunisation programmes for children in the Third World.

The Bill and Melinda Gates Foundation, a charity set up in 2000, made the donation to the Global Alliance for Vaccines and Immunization (Gavi) yesterday. The sum is more than 10 times the $63m donated by the UK government to the project.

"In just five years, Gavi's efforts have saved hundreds of thousands of children's lives, and its work in the coming years will save millions more," said Gates.

"But today's commitments are only a down payment. Rich countries can and should increase immunisation funding to give children in developing countries a better shot at a healthy life."

The latest donation brings Gavi's total budget to $2.3bn. However, the group estimates that it will need between $8bn and $12bn if it is to achieve total coverage for those in need.

Bill Gates will be sharing a stage with Tony Blair at the World Economic Forum in Davos next week to press world leaders on the need for greater effort in ensuring Third World health.

The Gates family are prominent philanthropists and the Bill & Melinda Gates Foundation was formed with the merger of Bill Gates's education charity and a foundation set up by his father William H. Gates.

William Gates last made the headlines when he formed a group of wealthy Americans in opposing George Bush's 2001 tax cut and the repeal of inheritance tax, stating that "taxing dead multimillionaires is eminently more fair than taxing the not-so-rich living".