Media playback is unsupported on your device Media caption Mr Soros said that HRW was one of the most effective organisations he supported

George Soros is to donate $100m (£65m) to Human Rights Watch (HRW) over the next 10 years, the investor and philanthropist has announced.

"Human Rights Watch is one of the most effective organisations I support," Mr Soros said.

The gift from Soros's Open Society Foundations is the largest the billionaire has made to a non-governmental organisation, HRW said.

It is given under the condition that HRW raises another $100m.

Mr Soros told the BBC's World Today programme that he wanted to see HRW grow.

"Human rights is a cause that I am deeply committed to and Human Rights Watch is an organisation that I know intimately and have very high regard for. And I support their plans for expansion," he said.

Mr Soros said he wanted to give the US-based group the kind of international support it deserved.

"Human rights is a universal principle," he said.

"The main advocate of human rights has been the United States and unfortunately the US has lost the moral high ground during the Bush administration so the fact that it is a US organisation sometimes makes them less effective than they would be if there were much broader support all over the world."

The gift is the first in a series of large donations he plans to make, Mr Soros said,

"This is partly due to age," the 80-year-old added, in remarks to the New York Times.

"Originally I wanted to distribute all of the money during my lifetime, but I have abandoned that plan."

HRW is to use the money to hire more staff and expand its work internationally, the group said in a statement.

The plan requires HRW to increase its annual budget from $48m to $80m within five years, the organisation added.

HRW, based in New York, currently has a staff of almost 300 and a presence in nearly 90 countries.

In October, Forbes Magazine estimated Mr Soros's fortune at $14bn (£9.1bn).