Master investor Warren Buffett may be lining up a bid for Bermuda-based insurer XL Capital, according to a rumour circulating on Wall Street yesterday.

American Mr. Buffett, 78, named last year by Forbes magazine as the world's richest man, has a personal fortune which was estimated at $62 billion last March.

The American owns US insurance giant Berkshire Hathaway, which has been buying up companies at an increasing rate during the ongoing credit crisis.

XL's shares climbed as much as 28 percent in New York Stock Exchange trading on the news yesterday, and closed up 10 percent at $3.93.

Bloomberg reported the rumour of Mr. Buffett's interest yesterday. The business news agency quoted Frederic Ruffy, the senior options strategist at WhatsTrading.com, a New York-based provider of options market analysis, as saying: "The shares were up on talk that Warren Buffett's Berkshire might be interested in taking a position in XL."

XL has seen its share price plummet, as it has lost more than $1 billion this year and has struggled with investment losses linked to the turmoil in world credit markets.

Jackie Wilson, a spokeswoman for Mr. Buffett, didn't respond to a request from Bloomberg for comment.