World soccer's governing body FIFA has told clubs they must release any players aged under 23 selected for next month's Beijing Olympics after rejecting a protest by three European teams.
In a statement issued to the clubs and the media on Wednesday, FIFA said Players' Status Committee member Slim Aloulou had ruled as a single judge that the release of players was mandatory for all clubs.
German Bundesliga sides Werder Bremen and Schalke, and Spain's Barcelona had argued against the need to release players because the Olympics were not included on FIFA's international match calendar.
"The single judge determined that the international match calendar is not of relevance in establishing whether clubs are obliged to release players," FIFA said in its statement.
"In view of the longstanding and undisputed practice (since 1988, clubs have always accepted the release of Under-23 players for the competition), he deemed that recourse to customary law is justified."
The statement added that the Olympic Games was a "unique opportunity" for all athletes "and that it would not be justifiable to prevent any player younger than 23 from participating in such an event".
Werder and Schalke have already filed complaints with the Court of Arbitration for Sport (CAS) following the call-ups of Schalke defender Rafinha and Werder playmaker Diego into Brazil's Olympic squad.
CAS said last week it would wait until after FIFA had made its final decision before examining the complaints.
Barcelona, whose influential forward Lionel Messi has been called up by Argentina, said on Monday they would also go to CAS if FIFA ruled against them.
The Olympic football tournament runs from Aug. 6-23, a period when many European clubs are beginning their domestic league seasons or playing qualifying matches for European competitions.
Barcelona are scheduled to play a two-legged Champions League qualifying tie in August.
Prior to FIFA's announcement, Messi told Spanish media that he would hook up with Argentina as soon as possible if the governing body insisted players should be released.
"I want everything to be sorted out," he was quoted as saying on the Barcelona website (www.fcbarcelona.com) on Wednesday.
"I understand the position of the club because a lot is at stake... But they also have to understand that it is my dream to play for my national team at the Olympic Games."
"From the beginning I've said that I want to play for my national team and I've never had problems until now.... If I get there and CAS says I have to come back then I will come back.
"For the moment I want to be with my national team and my team mates."
Although generally involving players aged 23 or under, Olympic squads are also allowed to nominate three overage players. FIFA has already acknowledged, however, that the release of those players was not compulsory.