Davos: Bill Gates, the Microsoft chairman and co-founder, announced that he was setting an example with the foundation set up by him and his wife, Melinda.

He said they were giving $306 million (209 million euros) to help millions of African farmers feed themselves and others and work their way out of poverty in a new green revolution using targeted technology and training.

The Bill & Melinda Gates Foundation, which has concentrated on improving health in poor parts of the world, has decided it is time to improve agriculture, he told reporters.

"Why do we think agriculture is so important?" Gates said. "Of the billion people who live on less than $1 a day, three-quarters are small farmers. And often it is actually the woman who is doing her best to both create crops for eating and earn some cash to buy other things."