French club Nantes have demanded payment from Cardiff City over the £15m transfer of Emiliano Sala, BBC Wales has learned.
Argentine striker Sala, along with pilot David Ibbotson, was on board the Piper Malibu N264DB which lost radar contact near Guernsey on 21 January.
Sala, 28, was Cardiff's record signing but never played for the club.
Cardiff have withheld the first scheduled payment until they are satisfied with the documentation.
The transfer fee is due to be paid in instalments over three years.
In a later interview with French newspaper L'Equipe, Cardiff chairman Mehmet Dalman indicated that Nantes had sent an invoice for the first instalment, worth 6m euros (£5.27m).
In the same interview Dalman added: "We must show respect to the family. There is the process of recovering the plane."
On Thursday night the Air Accidents Investigation Branch (AAIB) said a body had been recovered from the wreckage.
Cardiff had earlier expressed "surprise" that Nantes made the demand while the recovery attempts were under way.
It is understood Nantes are threatening legal action if they do not receive a payment within 10 days. The BBC has attempted to speak to Nantes for comment.
A source at Cardiff says they will honour the contract but not until they have clarified "all the facts".
It is unclear whether or not the club have insurance covering the cost of the transfer.
French club Bordeaux are also entitled to a cut of the fee, thought to be 50% - Sala was on their books from 2012 to 2015 before joining Nantes.
The plane carrying Sala and Ibbotson, from Crowle, Lincolnshire, disappeared en route to Cardiff after the footballer returned to Nantes to say goodbye to his former team-mates.