But profits from the Virgin Group's transport businesses, which make up nearly half the company, will also be spent on separate investments in biofuel research, development, production and distribution, and projects to tackle emissions through a planned Environmental Trust.

"We have to wean ourselves off our dependence on coal and fossil fuels. Our generation has the knowledge, it has the financial resources and, as importantly, it has the will power to do so," the flamboyant 56-year-old entrepreneur said.

Branson, who has a knighthood and is known as much for his daredevil stunts as his business, unveiled his plan at a news conference at the Clinton Global Initiative, a summit run by former US President Bill Clinton to combat world problems.

"Richard's commitment is groundbreaking not only because of the price tag -- which is phenomenal -- but also because of the statement that he is making: clean energy is good for the world and it's good for business," Clinton said.

The pledge comes one day after the Bush administration said it was committing US$3 billion to climate technology research and development. Climate experts and members of Congress criticized the administration's plan as long-delayed and inadequate.

FACING CATASTROPHE

Branson, whose Virgin Group has more than 200 companies worldwide and employs 25,000 people, said he used to be skeptical about climate change, but reading a lot of books on the issue changed his mind.

His decision to commit billions of dollars to the cause came after former US vice president and long-time environmentalist Al Gore visited him in England a year ago.

"He basically said 'look, you're in a position where you might be able to make an influence --if you could make a bold gesture then maybe other people will make a bold gesture as well'," Branson told the Clinton Global Initiative summit.

Branson said alternatives to conventional oils and coals were urgently needed.

"I really do believe the world is facing a catastrophe and there are scientists who say we are already too late, but I don't believe that is the case. The majority of scientists think we can still do something about it," he said.

Most international experts say emissions of greenhouse gases, mainly from burning fossil fuels in power plants, factories and cars, are the primary cause of a 1.1 F rise in temperatures over the past century.

A dwindling group of scientists say the dominant cause of warming is a natural variation in the climate system, or a gradual rise in the sun's energy output.