Chelsea could be facing a transfer embargo after it emerged Bertrand Traore appeared for the club’s Under-18s side aged just 16.
FIFA rules state minors (players aged under 18) are not allowed to complete international transfers, yet the Burkina Faso international took part in a friendly against Arsenal in 2011.
However, Chelsea believe Traore, who officially joined the club from Auxerre in January 2014, was the subject of an option agreement which allowed him to play in friendly games, report Press Association Sport.
Real Madrid and Atletico Madrid were handed transfer bans earlier this month for the next two complete windows after breaching the same regulations. Both clubs plan to contest the sanctions.
Barcelona were placed under a transfer embargo for infringing the same rules in 2014 and have only this month been allowed to register players again.
A FIFA spokesperson told Press Association Sport: “We are not in a position to comment on any investigations that are ongoing so as not to compromise the process, nor do we provide any comments as to whether or not any investigations are under way.”