LONDON: FIFA's punishment of Chelsea through a transfer ban over their signing of Racing Lens teenager Gael Kakuta is a warning shot to the game's biggest clubs, leading sports lawyers said on Thursday.

Chelsea said they would mount the "strongest possible appeal" after soccer's world governing body banned the Premier League club from registering new signings until 2011.

FIFA found Chelsea guilty of inducing Kakuta, now 18, to break his contract with the French club in 2007.