Chelsea and four other Premier League clubs are facing the threat of being hit with a transfer ban as part of Fifa's investigation into the signing of foreign players under the age of 18.
A report by French investigative website Mediapart has claimed that Fifa's integrity and compliance unit has internally proposed a two-year transfer ban on the London club stretching across four windows. Mediapart is one of the organisations publishing documents obtained by the website Football Leaks.
Chelsea, other than releasing a short statement in which they insisted they are cooperating with Fifa, would not comment on the report or the case. But sources close to the Fifa investigation have claimed that Chelsea are not the only Premier League club facing the possibility of a transfer ban. It is believed at least four others are under investigation and some of the biggest clubs in Europe are also being looked into.
A Fifa spokesman said: "As communicated in September 2017, investigations were opened concerning Chelsea FC as well as other English clubs in relation to potential breaches of the Regulations on the Status and Transfer of Players. The proceedings are ongoing and, to date, no decision has been passed by the Fifa judicial bodies. Thus, the clubs are to be presumed innocent unless decided otherwise. No further information can be provided as the cases are ongoing."
A source said: "This a massive investigation that will implicate a number of clubs. It will touch most of the big clubs around Europe and in the Premier League."
Fifa rules prohibit the international transfer of players under the age of 18 unless their parents have emigrated for reasons not connected to football or both the player and club are based within 50 kilometres of a national border.
The only other exception is for transfers within either the European Union or European Economic Area, where the minimum age is 16. In those cases, clubs must still ensure that the player continues his education and studies for an alternative career, as well as making sure he has a high living standard.
The investigation into Chelsea includes the signing of Bertrand Traore, who was pictured playing in an Under-18 game against Arsenal when he was 16.
The identities of the other four clubs under investigation have not been revealed, but Fifa has previously confirmed Manchester City's activities involving the signing of youth players were under review, even though the club denied any knowledge of the situation.
Mediapart have reported Fifa's integrity and compliance unit has recommended the Stamford Bridge side should be banned from signing players for one transfer window for the Traore signing, and three further transfer windows for 13 other offences, plus a fine of £384,000.