Warren Buffett, the investor who has vied with Bill Gates for the title of America's richest man, criticised the US justice department this weekend for its plan to split Microsoft into two.

"I'd not want to go in with a meat axe to something that's pulling this country along," he told shareholders to loud applause at the annual meeting of Berkshire Hathaway, his Omaha-based investment and insurance group.

Berkshire's vice-chairman Mr Charlie Munger also ridiculed the notion that "someone who's drawing a salary from the US government had the bright idea to dramatically weaken the one place where we're winning big".

Mr Buffett and Mr Gates are regular bridge and golf partners, and Mr Gates persuaded Mr Buffett last year to take a very small stake in the software company, in contrast to his usual aversion to technology-related stocks.

Microsoft and other technology companies had helped America "sweep the world aside", Mr Buffett said, to the point that "we're so far number one, it's difficult to see who's number two".

"This country had an inferiority complex about its place in the world," said Mr Buffett of the period when Microsoft was founded 21 years ago. "We talked about having a nation of burger-flippers . . . and it looked as though the Japanese and Germans were going to eat our lunch."

Microsoft and other technology companies had "contributed to a change in the national mood," Mr Buffett argued.

He added: "It is hard for me to see how Microsoft is sinful, because they've tried to improve their products every time, and make next year's business position stronger than last year's business position. If that's a sin, then every subsidiary of Berkshire's a sinner, I hope."