Multibillionaires Bill Gates and Michael Bloomberg launched a worldwide anti-smoking campaign, fuelled with $500 million of their money.

Microsoft founder Gates said he will donate $125 million toward the campaign, while New York Mayor Bloomberg said he would chip in with 250 million, on top of the 125 million he committed in 2005.

"Our goal is to support and complement the Bloomberg initiative," Gates said.

The campaign will back strategies to raise taxes on tobacco products, change the image of smoking in society, protect non-smokers from second-hand tobacco smoke and help smokers give up their habit.

Two of the world's wealthiest people, Bloomberg and Gates have for years donated part of their earnings to philanthropic enterprises.

A world without tobacco, said Bloomberg, "is a world in which people live longer and have happier lives."