Atletico Madrid have claimed that Barcelona still owe £72m in order to complete the signing of Antoine Griezmann.
After weeks of speculation regarding the attacker's future, Barcelona announced on Friday that they had finally brought in the World Cup winner on a long-term deal.
Barcelona intend to pay £108m, a fee designated in a clause in Griezmann's contract which only came into effect on July 1.
However, Atletico are arguing that an agreement was in place before that date, when the 28-year-old could only be signed for a set price of £180m.
A club statement read: "Atletico de Madrid believes that the amount deposited is insufficient to meet [Griezmann's] buy-out clause, since it is obvious that the player committed to FC Barcelona before the aforementioned clause was reduced from €200m to €120m.
"Atletico de Madrid believes that the termination of the contract occurred before the end of last season due to events, acts and demonstrations carried out by the player and that is why the club has already started the procedures it considers appropriate for the defense of its legitimate rights and interests."
Barcelona intend to officially unveil the player in the coming days.
