Enrique Cerezo claimed Atletico Madrid have evidence Barcelona had agreed to terms with Antoine Griezmann before his release clause dropped to €120 million.
Barca confirmed the signing of Griezmann on Friday on a five-year deal after a solicitor representing the forward deposited money for his buy-out clause at La Liga headquarters in Madrid.
The signing ends an extended saga involving the Frenchman and Barcelona, as Griezmann previously denied the club last summer to remain with Atletico Madrid.
However, Atletico believe the France international agreed to terms with Barca before his clause dropped from €200 million on July 1 and therefore claim they are owed an additional €80 million to ratify the transfer, they said in a statement.
Cerezo, the club president, said the La Liga outfit had proof that Griezmann and Barcelona negotiated early and planned to request a greater fee.
“If the club have made this statement it’s because there’s evidence,” he told RAC1.
“We have to study it and we’ll demand the amount we consider to be necessary.”