Washington, Aug 5 (IANS) Billionaires in the US are queuing up to give away half of their mind-boggling fortune to charity.

Investor Warren Buffett and Microsoft founder Bill Gates started the campaign to convince billionaires to join them to donate most of their wealth.

‘I’ve been surprised how much progress we’ve actually made,’ the New York Daily News Thursday quoted Buffett as saying.

‘We’re hoping that America, which is already the most generous society on Earth, becomes even more generous.’

The going had not been easy. Buffett and Bill and Melinda Gates had themselves called up 80 people on the Forbes list of the 400 wealthiest in the US. They now have 40 willing billionaires.

They asked them to sign the Giving Pledge, which is a vow to give away at least half of their fortune by the time they die or after their death.

Wall Street Journal reported that New York Mayor Michael Bloomberg will join Blackstone co-founder Peter G. Peterson and 38 other billionaires by parting with their wealth.

Bloomberg Wednesday told reporters that nearly all of his net worth, estimated at $17.5 billion, will be given away.

He said that he didn’t want to leave the bulk of his fortune to his children. He stressed the importance of not leaving his children ‘so much money that it ruins their lives’.

The donators include Bill Gates, Buffett, Microsoft co-founder Paul Allen, Bloomberg, pharmaceutical tycoon Patrick Soon-Shiong, Oracle founder Larry Ellison and Hollywood director George Lucas, Xinhua reported.

The list also includes David Rockefeller, from the Rockefeller family, and Barron Hilton, son of Hilton Hotels founder Conrad Hilton.

‘The pledge is a moral commitment to give, not a legal contract,’ a statement from the Giving Pledge said.

Buffett said the drive has ‘just started, but already we’ve had a terrific response’.