U.S. sports tycoon Malcolm Glazer is considering whether to bid for Manchester United Plc, a source close to the situation said on Friday, driving shares in the English soccer champions to three-year highs.

A bid from Glazer, owner of American football team the Tampa Bay Buccaneers and 16.3-percent shareholder in Manchester United, could spark a takeover battle valuing one of the world's most successful soccer clubs at more than 900 million pounds ($1.7 billion), analysts said.

The 125-year-old club's biggest investors, Irish race horse owners John Magnier and J.P. McManus, earlier this week raised their stake to 28.9 percent, near the 30 percent level at which they would be obliged by UK law to make a full takeover offer.

"If Glazer were to make a bid, and I think he will, I wouldn't be surprised if Magnier and McManus came back (with an offer)," said Tony Craze, a stockbroker with tonycraze.com who advises some small investors in Manchester United.

A winning bid would probably have to reach about 350 pence per share, or 928 million pounds, he added.

At 1050 GMT, Manchester United shares were up 4.9 percent at 280p, valuing the winner of 15 English soccer championships at about 741 million pounds. Earlier, the stock hit a 39-month high of 290p.

A profitable, debt-free business with one of the best-known brands in the world, Manchester United is prized by investors for its marketing potential. According to former Chief Executive Peter Kenyon, the club has 50 million fans across the world.

But supporters are wary of a takeover, which they fear could turn a historic club into a personal fiefdom and reduce the influence of ordinary fans.

OPTIONS

Glazer, who graduated from the family watch-parts shop to become to 244th richest man in the United States, has hired Commerzbank to consider his options over Manchester United, a source close to the matter told Reuters.

"He has hired Commerzbank but it is still unclear as to what precisely his agenda is," the source said. "Whether it actually winds up at a bid at the end of the day we don't know."

A spokesman for Manchester United said the club had regular talks with Glazer because of his shareholding and would continue to do so, but declined to comment on the prospects of a bid.

An industry source said the club had not received a bid approach from any parties.

Commerzbank declined to comment.

Speculation about a possible bid for Manchester United has swirled for months, as major shareholders built up their stakes and Russian billionaire Roman Abramovich swooped on London-based rivals Chelsea last year.

McManus and Magnier have been the most active investors, buying a 10 percent stake from pay-TV firm BSkyB last year and raising their holding earlier this week to 28.89 percent.

BSkyB, controlled by media mogul Rupert Murdoch, was blocked by competition regulators from buying Manchester United in 1999, when it offered 240p a share.

Sources close to Magnier and McManus, who are locked in dispute with the club over its player transfer policy, have declined to say whether they might be drawn into a bid.

While Tony Craze thought they would respond to a bid from Glazer, he said this would probably be just to raise the price.

"They're extremely canny investors... I think they'd see it (a bid from Glazer) as an opportunity to push the price higher", he said, arguing that if Magnier and McManus had wanted to bid for Manchester United they would have done so already.

Magnier is also in a high profile dispute with Manchester United team manager Alex Ferguson about the rights to prize-winning race horse Rock of Gibraltar.