Antoine Griezmann reportedly struck an agreement with Barcelona regarding his signing-on fee despite still being an Atletico Madrid player back in March.
The Frenchman, who spent five years with Atletico, completed a move to Camp Nou worth £108m earlier this summer.
However, Atletico believe that they are owed an extra £72m due to the deal being agreed before July 1, when Griezmann's buy-out figure was still at £180m.
According to Mundo Deportivo, emails prove that Griezmann, his sister Maud, his father, his lawyer Sevan Karian and a French agent were given a total of £12.3m as a signing-on fee back in March.
In response to these reports, which first emerged last month, Barcelona have insisted that the emails fail to imply any evidence of direct negotiations with Atletico because they were not sent to a club employee.
The same publication claimed that, along with a negotiated signing-on fee, the emails also contained draft salary proposals for Griezmann's contract at Barcelona.
