Football clubs must release under-23 players for the Beijing Olympics, FIFA ruled Wednesday, according to dpa. The decision of the single judge of the Players' Status Committee, Tunisian Slim Aloulou, was taken after football's ruling body received requests for clarification from Barcelona and from the German football federation (DFB) on behalf of Schalke 04 and Werder Bremen. In a statement, FIFA said "that the release of players under the age of 23 for the Men's Olympic Football Tournament Beijing 2008 is mandatory for all clubs. Previously, on 29 July 2008, the FIFA Emergency Committee also took a decision in the same sense." The ruling comes after Schalke announced earlier this month the start of proceedings to go before the Court of Arbitration for Sport (CAS) over their 22-year-old Brazilian defender Rafinha. Schalke argued that the men's Olympic tournament was not on the international calendar so they were not obliged to release the player but FIFA ruled that this was not relevant. "The single judge determined that the international match calendar is not of relevance in establishing whether clubs are obliged to release players for the Men's Olympic Football Tournament," said FIFA. "In this regard, 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 Olympic tournament is by definition an under-23 event but each team can field three overage players who the clubs are not required to release. Apart from Schalke, Werder Bremen didn't want to release their Brazilian Diego while Barcelona wanted to prevent star forward Lionel Messi from playing for 2004 gold medallists Argentina in Beijing. "We have to look now and see if it makes sense to continue with a case," Bremen CEO Klaus Allofs told Deutsche Presse-Agentur dpa. "It has to have a chance of being successful."