LISBON (Reuters) - Sporting said on Friday they have filed a complaint to world soccer's governing body FIFA over their former winger Gelson Martins joining Atletico Madrid on a free transfer, asking for the La Liga club and the player to be sanctioned.
"Faced with the unacceptable behaviour of Atletico Madrid in the process of signing the player Gelson Martins, the board of Sporting Lisbon has unanimously decided to file a complaint to FIFA against the club and the player, asking for them both to face sporting sanctions," said a statement from Sporting.
Atletico and FIFA were not immediately available for comment.
Martins rescinded his contract with Sporting last month, one of nine players to quit the Lisbon club after an attack in May on a training camp by fans in which Dutch forward Bas Dost was injured and the dressing room was vandalised.
The incident came at the end of a tumultuous campaign for Sporting who finished third in the Primeira Liga and reached the Europa League quarter-finals where they lost 2-1 on aggregate to eventual winners Atletico. Martins played in both legs.
Reports in the Portuguese media say Sporting are asking for compensation of between 60 million ($69.9 million) and 100 million euros.
Sporting have also complained to FIFA over Rui Patricio joining Premier League side Wolverhampton Wanderers as a free agent after the Portugal goalkeeper also cut ties with the club following the training ground incident.
(Reporting by Richard Martin; Editing by Christian Radnedge)