Paris Saint-Germain have appealed to the Court of Arbitration for Sport (CAS) to stop UEFA re-examining their decision to clear the club of breaching Financial Fair Play (FFP) regulations.
European football's governing body opted to review the investigation in July, having cleared the Ligue 1 champions of contravening FFP a month earlier.
PSG, who in 2017 signed Neymar for a world-record €222million and Kylian Mbappe on an initial loan before making the deal permanent for €180m, raised funds of around €50m through transfers at the request of UEFA to avoid sanctions for the 2015, 2016 and 2017 financial years.
A statement from CAS read: "The Court of Arbitration for Sport (CAS) has registered an appeal filed by the French club Paris Saint-Germain Football SASP (PSG) against a decision rendered by the European Football Association (UEFA) in September 2018.
"At the parties' request, the procedure will be conducted on a confidential basis with the exception of the final Award which will be published.
"In these circumstances, CAS is unable to provide any further information regarding the matter."