Zurich, (Agencies): FIFA is looking into the transfer of South Korea international Koo Ja Cheol to VfL Wolfsburg following the request of the Swiss Federation which says a Swiss club had an earlier contract with the player.

Koo is said to have signed a deal with Young Boys Berne, but there was allegedly no transfer deal between Berne and his Korean club Jeju United.

Wolfsburg said Wednesday they did nothing wrong when they signed Koo until 2014 earlier in the week.