Chelsea have been hit with a stunning transfer ban by Fifa which will prevent the club signing any new players until January 2011.
The London club have been found guilty of inducing French teenager Gael Kakuta to breach his contract with previous side Lens.
Fifa's dispute resolution chamber (DRC) today announced Chelsea will be banned from registering any new players for the next two transfer windows - effectively January 2011 will be the next time they can make a new signing unless they win an appeal.
A Fifa spokesman told Press Association Sport: "This decision confirms our aim to ensure contractual stability. It is an important ruling for football in general."
Chelsea have been ordered to pay £115,000 (130,000euros) training compensation to Lens, and are also liable for the £680,000 (780,000euros) compensation sum ordered against Kakuta himself, who is banned from playing any games for four months.
Kakuta, 18, joined Chelsea from Lens two years ago after which the French club lodged a complaint with Fifa asking for compensation and for sporting sanctions against the London side.
Fifa said in a statement: "The French club had lodged a claim with Fifa seeking compensation for breach of contract from the player and requesting also sporting sanctions to be imposed on the player and the English club for breach of contract and inducement to breach of contract respectively.
"The DRC found that the player had indeed breached a contract signed with the French club. Equally, the DRC deemed it to be established that the English club induced the player to such breach.
"A restriction of four months on his eligibility to play in official matches is imposed on the player Gael Kakuta while the club FC Chelsea is banned from registering any new players, either nationally or internationally, for the two next entire and consecutive registration periods following the notification of the present decision."
Chelsea have the right to appeal against the decision and take the case to the Court of Arbitration for Sport in Lausanne.
Given the severity of the punishment, it is almost certain the club will take that course of action.
Kakuta, a skilful left-winger, is viewed as Chelsea's most promising young player. He ended his first season as top scorer in the youth side and was voted the Academy's player of the year.
His second season was brought to an abrupt end in February by a double fracture of his ankle.
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