World football’s governing body, Fifa is investigating alleged violations in rules when it comes to signing players under the age of 18.

According to leaks by French website Mediapart, the investigation has been ongoing for three years and could lead to Chelsea being banned from four transfer windows over two seasons.

In a statement, Fifa outlined: “As communicated in September 2017, investigations were opened concerning the club 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.”

It’s currently Fifa rules that clubs can’t transfer players under the age of 18 unless the players’ parents have emigrated to the country for reasons not related to football. There are exceptions to this rule, regarding the the European Union or European Economic Area.

Chelsea’s activity surrounding tricky Burkina Faso winger, Bertrand Traoré after the player played for the club’s under-18s in a tie against Arsenal as the age of 16, before being officially announced as a Blues’ player on the first transfer deadline after his 18th birthday.

In the past Spanish giants, Barcelona and Atlético Madrid have been sanctioned for rule breaches when it comes to signing players under the age of 18, both clubs served two year transfer suspensions.