Lord Triesman has ruled out Sir Alex, the most successful manager in the history of British football, because he has an agreement that he will not appoint a Scotsman to oversee preparations for the London Games.

Sir Alex, who has won during 30 trophies since becoming manager at Manchester United in 1986, including the Champions League twice and the Premiership on 11 occasions, had been approached by both the Primie Minister Gordon Brown and Sebastian Coe, the chairman of London 2012, to see if he would be interested in managing the British team.

But the three other Home Countries - Scotland, Wales and Northern Ireland - have refused to take part in a united British team because they fear it would jeopardise their independence to compete in events like the World Cup and European Championships.

Britain will be represented by an all-England team at London 2012.

Triesman has, therefore, been forced to rule out Sir Alex as a candidate.

Triesman said: "We cannot appoint a Scot, Welshman or Northern Irishman because that would go against our agreement with the other Home Nations.

"It would be very desirable to have an English coach."

Triesman hopes to appoint a coach later this year with Stuart Pearce, the former England captain who is now managing the country's under-21 team, the leading contender.

The ex-Nottingham Forest and Newcastle United left-back has already said that he wants the job and in May 2008 was appointed as the FA's chief adviser on the Olympics, which included travelling to Beijing for last year's Games.

Triesman said: "I would be very disappointed if we have not appointed a coach for the Olympic team by the end of this calendar year.

"The age of the coach is not as important as his ability to get the best out of young players, some of whom might still only be 17, 18 or 19 now but 20 or so when the Olympics come around.

"I think the coach needs that length of time to identify the players who will make up his squad and start working with them to develop a team spirit.

"Having a foreign coach is not entirely out of the question but it will be fantastic to have an Olympics on home soil so it would be great to have a home-grown coach if we can.

"The most important thing is who would be the best person and we also have to ensure any appointment does not interfere with the preparations for the 2010 World Cup.

"I'm not going to speculate about names but I'm a great admirer of Stuart Pearce and I think his work with the under-21s has been superb.

"He got an English team through to a final [this year's Euro under-21 championship] for the first time for quite some time.

"He could be someone who fits the profile."

But Roy Hodgson, the manager of Fulham who coached Switzerland at the 1994 World Cup, is also being considered.