Atletico Madrid have lodged an appeal against their two-window ban on registering new players with FIFA.
On January 14, Atletico and Real Madrid were handed sanctions by the governing body's Disciplinary Committee as a consequence of breaches "relating to the international transfer and registration of players under the age of 18".
After studying the documentation, Atletico have notified the FIFA Appeal Committee of their desire to contest the punishment.
The club have maintained their innocence and have requested the ban be suspended until a decision on the appeal is reached.
A statement read: "We consider that we have acted within the law in all cases. In addition, we request the probationary suspension of the sanction pending the outcome of the appeal."