Atletico Madrid have released an official statement to condemn Barcelona's behaviour during their pursuit of Antoine Griezmann.
The La Liga runners-ups revealed at the end of the season that Griezmann would end his five-year spell at the club this summer, seemingly paving the way for a switch to Camp Nou.
However, a transfer is yet to materialise, despite the suggestion that Griezmann and Barcelona officials have been in negotiations since February.
Atletico responded with a lengthy statement on Friday, criticising the conduct of the Catalan giants during a process which remains ongoing.
Posted on the club's official website, it read: "On May 14, Antoine Griezmann informed Diego Simeone and Andrea Berta of his decision to leave our club at the end of the season. In the days that followed that meeting, Atlético de Madrid learned that FC Barcelona and the player had reached an agreement in March, specifically in the days following the return match of our Champions League tie against Juventus, and that they had been negotiating the terms of the agreement since mid-February.
"Regarding president Josep Maria Bartomeu's statement today we wish to state that it is true that yesterday there was a meeting between Miguel Angel Gil and FC Barcelona CEO Oscar Grau, at Barcelona's request and that at that meeting, Mr Grau expressed his intention, once the release clause of Antoine Griezmann's contract had decreased from 200 to 120 million euros, to ask for a deferred payment of the aforementioned amount of the clause in force as from July 1.
"Atlético de Madrid's response was obviously negative, as we believe that FC Barcelona and the player have disrespected Atlético de Madrid and all its fans. As a consequence, today, Atletico de Madrid has instructed the player, his sister and agent and his lawyer, that Antoine Griezmann, in compliance with his contractual obligations with our club, must appear next Sunday in the club's facilities in order to start the pre-season with the rest of his teammates.
"Through this statement, Atletico de Madrid wishes to express its strongest disapproval of the behaviour of both, especially FC Barcelona, for prompting the player to break his contractual relationship with Atletico de Madrid at a time of the season when the club was involved in the Champions League tie against Juventus, as well as the league title race against FC Barcelona, something that we believe violates the protected periods of negotiation with players and alters the basic rules of integrity in any sporting competition, as well as causing enormous damage to our club and its millions of fans."
Atletico have already moved to replace Griezmann with Benfica youngster Joao Felix.