Nantes have reportedly rejected a proposal by Cardiff to settle Emiliano Sala's transfer fee after the player tragically died in a plane crash in January.
FIFA are expected to intervene on Wednesday in Switzerland with the Ligue 1 side still demanding the previously agreed £15million excluding bonuses at the beginning of the year.
FIFA will formally give notice of their decision at the beginning of next week which both clubs would be able to appeal to the Court of Arbitration of Sport (CAS) according to L'Equipe.
Cardiff allegedly refused to pay the fee for the Argentine striker after Sala's body had been found.
The Piper Malibu light aircraft crashed 22 miles off Guernsey on January 21 while travelling from Nantes to Cardiff, and Sala's body was found in the wreckage.
The body of pilot David Ibbotson has never been found.
Air Accidents Investigation Branch (AAIB) report in February into the crash called into question the legitimacy of pilot Ibbotson flying Sala to Nantes in a plane which crashed on the return trip.
Cardiff were thought to feel that the AIIB report calls into question both the choice of pilot - whose qualifications were not of the higher criteria needed to make commercial flights – or the choice of plane: a single-engine, single-propeller craft, rather than a private jet.
Cardiff's position at the time was that their offer to Sala of a commercial flight back to Nantes, via Paris or Amsterdam, on the fateful weekend was 'overridden by the agent' - Willy McKay, whom Nantes had engaged to find a buyer for Sala.
