Atletico Madrid have asked La Liga to block French forward Antoine Griezmann's move to Barcelona in a dispute over the transfer fee between the two clubs, according to the Spanish league's president Javier Tebas.
Spanish champions Barcelona announced the signing of Griezmann this month for 120 million euros ($133.75 million) but Atletico complained that the Catalan club had not paid enough to trigger the player's release clause.
The buy-out clause had dropped from 200 million euros to 120 million euros on July 1, but Atletico claim that Griezmann's May 14 announcement that he was leaving the club is proof a deal was struck between the player and Barcelona much earlier.
"(Atletico) submitted a complaint and put in doubt whether we should pass Griezmann's licence to Barcelona," Tebas told Spanish radio station Onda Cero on Wednesday.
"There's a process that has been put in motion and those overseeing it will have to come to resolve the case.
"It is possible to block a player's transfer. La Liga will have to decide what course of action to take."
Griezmann has already played a friendly for his new club, a 2-1 defeat by Chelsea in Japan on Tuesday.