Continuing a lifelong habit of putting money where his mouth is, George Soros has announced a gift of US$100 million ($139 million) to Human Rights Watch, the organisation which seeks to monitor abuses of power and to lobby transgressing governments and companies.

The billionaire financier - known as the "man who broke the Bank of England" for betting that the pound would drop out of the European Exchange Rate Mechanism in 1992 - said the gift was one of a series he planned to give to liberally minded charities and campaign groups.

The donation will put the once-small group into the same league as organisations such as Amnesty International. It will allow Human Rights Watch to add 120 members of staff to its 300-strong payroll, and almost double its annual budget to US$76 million, meaning it could expand operations in such countries as South Africa, China and India.

The New York-based group, founded in 1978, devotes most of its manpower to forensic investigations into human rights abuses. It then typically publishes hard-hitting reports into the people and organisations who might be held responsible.

It shared the Nobel Peace Prize in 1997 for co-founding the campaign to ban landmines, and has recently published reports on child slavery at Islamic schools in Senegal and worker abuse at farms in Kazakhstan where Philip Morris sources large amounts of tobacco.

In March, Libya released 200 political prisoners in response to a Human Rights Watch report into its justice system. The Chinese Government has also moved to close down so-called "black prisons" which were documented in one of the group's publications earlier this year.

Soros, who is worth an estimated US$14 billion, and is thought to be the world's 35th wealthiest man, said he hoped the gift would help to restore America's "lost" reputation for exporting freedom and democracy.

"The US has lost the moral high ground under the Bush Administration," he said. "There have been many human rights violations committed by Americans. And that has endangered the credibility, the legitimacy, of Americans being in the forefront of advocating human rights."

Soros, who is 80, has first-hand knowledge of human rights abuses. He was born into a Jewish family in Budapest, and survived the Nazi occupation of Hungary before emigrating initially to Britain and then to the US. There he built a large fortune through investment and currency speculation.

His gift to Human Rights Watch is by far the largest the group has ever received, and is the second-biggest donation of any sort made by an individual so far this year. Soros made it clear yesterday, however, that there is more where it came from: several other large gifts will be announced in the coming months.

"This is partly due to age," he said. "Originally I wanted to distribute all of the money during my lifetime, but I have abandoned that plan.

"My foundation should continue, but I still would like to do a lot of giving during my lifetime, and doing it this way, with such size, is a step in that direction," he added.

This year, Soros has distributed US$700 million, including US$4 million to Haiti after January's devastating earthquake, and US$5 million to disadvantaged schoolchildren in New York.

Some of his gifts are more controversial: he recently upset conservatives in the US by helping fund, a website which monitors alleged racism in the so-called Tea Party movement.