Atletico Madrid have told Barcelona "enough is enough" following further reports that the Catalan club will pay Antoine Griezmann's release clause this summer.
Cadena Cope claimed on Tuesday that Barca have already told Atletico of their plans to pay the €100 million fee which would allow them to bring the France forward to Camp Nou.
However, a high-ranking Barcelona source told ESPN FC they "can't possibly believe that is true" at this moment in time.
The latest development comes just days after Barca president Josep Maria Bartomeu and striker Luis Suarez spoke openly about the La Liga champion's interest in Griezmann.
Suarez, talking as if the deal was already done, said that Griezmann will be "welcome" at Barca and Bartomeu confirmed that he met with the Atletico player's agent last October.
It's all been too much for Atletico, who responded late on Tuesday in the form of a furious statement attributed to their CEO Miguel Angel Gil Marin.
"We're fed up with Barcelona's attitude," Gil Marin said. "That a president and a player speak the way they've done about the future of a player with an existing contract -- and just a few days before disputing a European final -- shows an absolute lack of respect towards Atletico Madrid and the club's fans.
"Atletico's stance is very clear and has been made public on numerous occasions. Not once have we negotiated for Griezmann, nor do we have any intention to do so. A few months ago, I personally expressed to [Bartomeu] that our player isn't for sale nor are we going to sell him.
"At the same time, I let him know that his inappropriate conduct was against the integrity of the competition, especially since we've been competing for the league title throughout the season and Barcelona have been continuously pressuring one of the most important players."
However, should Barca pay Griezmann's buyout clause at the end of the season, there's little Atletico can do in theory to stand in the way of a transfer -- a situation they themselves benefitted from when they signed Vitolo from Sevilla last summer.
Gil Marin, though, says the Rojiblancos will not let the matter go easily and suggested they will take action.
He added: "I also told [Bartomeu] that in the chance the player exercises his right to nullify his contract due to their pressure throughout the season, that Atletico Madrid would demand Barcelona compensation for their inappropriate behaviour.
"Enough is enough. I hope this statement serves its purpose and that us Atletico fans can enjoy this moment and prepare ourselves for a final like we should."
The transfer saga has been rumbling on for months, with Barca already forced to release a statement in January denying they had held talks with Griezmann's family following some clumsy comments from director Guillermo Amor.
Griezmann looked set to leave Atletico for Manchester United last summer until he performed a U-turn, deciding to stay put out of loyalty after the club had their transfer ban upheld.
He's left his future beyond this season up in the air, though, and said last week that he's waiting on the result of talks with Atletico before deciding his future amid the constant speculation.
Earlier this season, he revealed that he expects everything to be cleared up, one way or another, before he heads off to the World Cup with France this summer.