Bill Gates, chairman of IT behemoth Microsoft and the world's richest man, has donated $750 million to the Global Alliance for Vaccines and Immunisation (Gavi) which helps fight deadly vaccine-preventable diseases among the poorest children in the world, said a report in The Guardian.

This donation is the biggest ever for Gates and also one of the largest one-time donations ever by a living philanthropist, The Guardian said on Tuesday.

Gates helped set up Gavi in 2000; and till date the Bill and Melinda Gates Foundation has made donations to the tune of $1.5 billion to Gavi.

At the same time, the government of Norway too announced a grant of $290 million to Gavi for the stellar work the alliance is doing in helping immunise poor children the world over.

Bill and Melinda Gates also urged other governments to grant funds for this cause and meet the World Health Organisation's target of $12 billion over a decade and help more than 90 per cent of the globe's children to be immunised against deadly diseases.

Gavi is an alliance of governments, UN agencies, NGOs and other institutions.

The Guardian said that almost 27 million children are not immunised each year.

The Bill and Melinda Gates Foundation, formed in 2000, has so far committed grants to the tune of $7.5 billion to various global projects.