Jacques Rogge, the President of the International Olympic Committee (IOC), said today that he has warned world governing body FIFA that the sport risks elimination if it adopts controversial proposals to make the tournament an event only open to under-21 players.

Rogge said he has made clear to FIFA President Sepp Blatter that the IOC will reduce the number of teams if FIFA goes through with the change.

That could mean reducing the men's field for the 2012 London Olympics from 16 to 12 teams or, in the extreme scenario, dropping the sport altogether.

Rogge said: "I'm not going to enter in hypothetical situations and speculation.

"It is clear and FIFA know it, that the ultimate eligibility rules will affect the size of the competition format.

"It relates to the value of the event.''

Under current rules, the Olympic tournament is for players 23 and under.

Teams are also allowed to field three "over age'' players.

The restrictions were put in place by FIFA, with IOC approval, to protect the supremacy of the World Cup as the sport's premier competition.

The FIFA Executive Committee recently said it wanted to limit the tournament to players 21 and under, or eliminate the rule on allowing three players over 23.

The IOC's ruling Executive Board is monitoring the situation and prepared to act.

Rogge said: "I said clearly to Sepp that the IOC is happy with the current system.

"I said very clearly to Sepp Blatter that a change downwards for the eligibility rule would definitely diminish the appeal of the tournament.

"Sepp knows exactly that this would affect the format of the tournament.''

"They know exactly what we want.

"We'll wait and see what they're doing.''

If the rules remain unchanged, that could allow the likes of Rooney, who will be 26 by the time of the London Games, to join Britain's team, which will be made up entirely of English players.

Blatter has said that teams that qualify for FIFA's under-20 World Cup, which is played every two years, could be chosen to compete in the Olympics the following year.

FIFA put off a decision on the Olympic rules at its Congress in Nassau earlier this month. Blatter said he was forming a special commission to further study the issue.

Rogge said: "There were probably different views,.

"It seems to be clear that some continents did not want to change the rules and some did want to change the rules.

"Being a wise man, Sepp Blatter took it out of the agenda.''

In addition, Rogge has asked Blatter to put the Olympics on FIFA's "combined programme'' - the list of competitions for which clubs are required to release their players to national teams.

At last year's Beijing Olympics, where Lionel Messi helped Argentina to the gold medal, several European clubs fought to keep their players out of the games.

Rogge said: "For some reason, the Olympics program is not on this combined program, and that would have avoided lots of the problems we had in Beijing.

"We said to FIFA: please keep [the under-23 format] as it is and put us on the programme.'

Rogge said he will contact Blatter immediately after this month's Confederations Cup in South Africa to pursue a "sensible solution.''

He said organisers of the 2012 London Olympics need to know soon what format the tournament will take.

Rogge said: "We cannot let London be in uncertainty for too long,.

"I will ask Sepp Blatter to make haste.''