A group of wealthy supporters is looking into a possible bid for English soccer club Manchester United, though the club's billionaire U.S. owners say it is not for sale.

The 'Red Knights', a collection of individuals including former Football League chairman Keith Harris, said on Tuesday they were looking at the feasibility of putting together a bid for the world's third richest soccer club.

However, they said discussions were at an early stage and they had not made contact with club owners, the Glazer family.

The Glazers, who also own the Tampa Bay Buccaneers American football team, bought United in 2005 for about 790 million pounds against a wave of opposition from fans who feared they were loading it up with too much debt.

"Manchester United Football Club is not for sale," a spokesman for the Glazer family told Reuters on Tuesday.

Wyn Grant, professor of football economics at Warwick University, said any offer was likely to have to exceed 1.2 billion pounds to tempt the Glazers.

KNOWLEDGEABLE PEOPLE

"If you offer them 1 billion pounds they (the Glazers) are just getting a 25 percent return over five years which is not terribly good," he said in response to newspaper reports the Red Knights were considering a bid at around that level.

"Clearly the people they have got in the consortium are very experienced and knowledgeable people, but it would take significantly more than 1.2 billion pounds in my opinion (to win over the Glazers)," he said.

United are the world& apos;s third wealthiest soccer club behind Spain's Real Madrid and Barcelona, but their debts have swelled to about 716.5 million pounds to the consternation of many fans.

A growing number have been protesting by shunning the side's red and white colours and sporting green and gold, worn when the team was known as Newton Heath in its early days.

"Any new ownership model would aim not only to put the club on a sound financial footing but would also aim to put the supporters at the heart of everything the club does," the Red Knights said in a statement.

The Manchester United Supporters Trust (MUST) said in a separate statement it was working with the Red Knights.

Duncan Drasdo, MUST's chief executive, told reporters the group had been in discussions with the Red Knights for some time.

EXCEPTIONALLY POSITIVE

"The Red Knights group coming out is exceptionally positive for supporters who want to see a change of ownership," said Drasdo said.

"All Manchester United supporters should now seize this opportunity with both hands and say they want a change of ownership.

"It's not boycotts or protests, I would call this a movement for change and rather than being unsettling I think the green and gold campaign has been tremendously positive in terms of the attitude in the stands."

MUST's membership has more than doubled in recent months from 27,000 to 55,000 registered members and they have set an initial target of 100,000 members in their fight for change.

As well as Keith Harris, who is executive chairman of stockbrokers Seymour Pierce, the Red Knights include Goldman Sachs economist Jim O'Neill; Mark Rawlinson, a partner at law firm Freshfields; and Paul Marshall, co-founder of hedge fund Marshall Wace, a person familiar with the matter said.

The individuals were not immediately available for comment and the Red Knights declined further comment.

Meanwhile, the club reported on Tuesday an improved financial performance in the first half of its fiscal year to December 31, boosted by an increase in television revenues from the UEFA Champions League competition.

Revenue increased by 19 percent to 144.7 million pounds with media revenue up 33 percent and matchday revenue rising 10 percent, benefiting from two extra Premier League games in the period.

The club cut its pretax loss to 1.9 million pounds during the half year, compared with 23.9 million the year before.

(Additional reporting by Mark Potter, Mitch Phillips and Matt Scuffham; Editing by Mark Potter and Ken Ferris)