One of the world's richest men has decided to devote more time to philanthropy. Bill Gates said he will gradually remove himself from daily duties at Microsoft Corp. over the next two years.

"This was a hard decision for me," Gates told the Associated Press Thursday. "I'm very lucky to have two passions that I feel are so important and so challenging. As I prepare for this change, I firmly believe the road ahead for Microsoft is as bright as ever."

Gates started the company with Paul Allen in the 1970s, and helped it become the largest software developer in the world. About 90 per cent of personal computers operate on various versions of Microsoft's Windows program.

Gates and his wife Melinda used their wealth to start the Bill & Melinda Gates Foundation, formed in 1999 from two previous charity groups. The organization has about $29.1 billion US at its disposal, funding efforts to ease poverty, and improve technology and pubic health in developing countries.

"We think this is excellent news," said Anne Lynam Goddard, chief of staff at CARE, which received nearly $10 million US from the foundation in 2005. CARE fights global poverty, with an emphasis on helping women.

"I can only imagine Bill Gates giving his total attention to the Gates Foundation's work will raise the bar on what their contribution can be in the world in these areas," said Goddard.

Gates and his wife are both co-chairs of the foundation, along with his father, William H. Gates Sr.

When Gates first started the charity organization, he sought advice from Vartan Gregorian, president of the $2.2-billion-US Carnegie Corporation of New York.

The Carnegie Corp. was founded by Andrew Carnegie, a 19th-century Scottish immigrant and self-made millionaire, who devoted himself to philanthropy at age 65.

"Bill Gates always has believed that with wealth comes responsibility, the same as Andrew Carnegie," said Gregorian.

"There are people who deal with symptoms -- somebody is poor, you give money. That's charity. Philanthropy ... is to solve problems through investment and planning, not (just) through generosity."

He added that when Gates decided to focus his efforts on building the foundation, he never lost his focus, even when the U.S. government brought an antitrust case against Microsoft in the 1990s.

"At the height of that lawsuit as we met in a foundation meeting, he never, ever took a phone call or went out to do other business," said Gregorian.

With files from The Associated Press