Bill Gates and Warren Buffett think fellow US billionaires should donate most of their vast fortunes to charity – and they revealed that 40 are set to do just that.

“Forty of the wealthiest families and individuals in the United States have committed to returning the majority of their wealth to charitable causes,” said a statement released by www.givingpledge.org.

The Giving Pledge, announced just six weeks ago, is the brainchild of Microsoft mogul Gates and investment guru Buffett who want to convince the richest people in the country to give 50 percent or more of their fortune to charity. The group includes CNN founder Ted Turner, New York Mayor Michael Bloomberg, Oracle co-founder Larry Ellison and Hollywood director George Lucas, as well as Mr Buffett and Mr Gates.

Mr Buffett said they simply started working their way through Fortune magazine’s list of 400 US billionaires, who between them have an estimated net worth of $1.2 trillion.

“We probably called somewhere between 70 and 80 people on the Forbes list. It was a very soft sell, but 40 signed up,” the chief executive officer of investment firm Berkshire Hathaway told reporters in a conference call. “We’ve made a terrific start.”

The idea is to squeeze morally-, not legally-binding pledges from the super wealthy.

There’ll be no group decisions on how money is spent or when. Instead, club members are to set an example by funding philanthropic pet projects, such as health, education and arts – and preferably sooner rather later.

“You don’t have to wait to die to give it away,” said Mr Bloomberg, a media entrepreneur and major philanthropist whose worth is estimated by Forbes at $18 billion. “It never made a lot of sense to me why you’d want to change the world for better and not be around to see it.”

Almost all on the list are self-made, such as Bloomberg, and are worth about $1 billion, or far more. A few represent longer-established fortunes, including David Rockefeller.

They are not talking about taking vows of poverty. Bloomberg said he would ensure that his children were never destitute.

But he still has more than he can ever need. “You can’t spend it if you have over a certain amount,” he explained.

US billionaires have been out of favour with the public and politicians since the 2008 financial collapse. The pledge scheme might burnish their image.

“Business people are pretty widely mistrusted and seen as overwhelmingly self-interested,” conceded investment banker and newly signed-up pledge member Tom Steyer during the conference call.

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