Chelsea are being investigated by FIFA for breaching their regulations around youth players. FIFA have confirmed to Sportsmail that they have launched an inquiry into Chelsea's conduct involving signing foreign players under the age 18. The game's world governing body is now conducting a thorough investigation into potential impropriety. Atletico Madrid are currently under a transfer ban for breaching FIFA rules over the signing of minors. They appealed the decision, but it was upheld by CAS. Real Madrid were also punished last year, but had their ban reduced from two transfer windows to one. Although it is not believed Chelsea's case is as serious as the two La Liga clubs, it will be up to FIFA what sanctions they bring when they have concluded their investigation.