Mr Gates insisted he wasn't leaving the company he founded but was "reordering" his priorities to concentrate more on his health and education work at his charity, the Bill and Melinda Gates Foundation.

He will still be at the helm of Microsoft until 2008, while the firm goes through a transitional period, the BBC reported.

Mr Gates said:

"I'll be working as hard as I ever have during these next years.

"I'm very lucky to have two passions that I feel are so important and so challenging."