Nantes have demanded Cardiff City pay them for the transfer of Emiliano Sala.
The striker had agreed a £15m move to the Premier League but was on board a plane which lost radar contact across the English Channel on 21 January.
It is understood the transfer fee is due to be paid in instalments and, according to the BBC, the French side want payment.
The Argentine was Cardiff’s record signing and have reportedly withheld the first scheduled payment until they are satisfied with the documentation.
It is believed Nantes are threatening legal action if they do not receive a certain sum within 10 days.
A source at Cardiff is quoted as saying they will honour the contract, but not until they have clarified “all the facts.”
The missing plane was located at the start of February and investigators are now attempting to recover the body located in the wreckage of the aircraft carrying Sala and pilot David Ibbotson.
It’s a story that has shaken the football world and it has even led to a crowdfund raising more than €300,000 to continue looking for the missing Piper Malibu after authorities called off the search three days after the incident.