FIFA are investigating Emiliano Sala's transfer from Nantes to Cardiff City following a claim from the French club, the global football body said on Wednesday.

Sala had completed his record £15 million transfer to Cardiff from Nantes before boarding the Piper Malibu aircraft piloted by David Ibbotson for the Welsh capital on Jan. 1. The aircraft disappeared from air traffic control radar over the English Channel, prompting a fruitless three-day search of the area by authorities.

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Sala's family financed a further search through a crowdfunding campaign which found the aircraft and the player's body on Feb. 7. Mr. Ibbotson's body has not yet been found.

Cardiff have yet to pay for Sala and Nantes have appealed to FIFA to intervene.

"We can confirm that we have received yesterday evening a claim from FC Nantes against Cardiff City in connection with the transfer of Emiliano Sala. We are looking into the matter and consequently we have no further comments at this stage," a FIFA spokesperson confirmed to ESPN FC.

A statement from Cardiff read: "Cardiff City remains committed to ensuring fairness and accountability with respect to the agreement between Cardiff City and FC Nantes, but first and foremost the relevant authorities must be allowed to determine the facts surrounding this tragedy. It is inappropriate to comment further at this stage."

The original deadline for the first payment of £5.8 million was Feb. 16, before it was moved to Feb. 27, and the transfer was officially registered by FIFA so Nantes feel they are within their rights to demand payment.

Sources close to the deal have told ESPN FC that Cardiff have yet to contact Nantes over the transfer and the Ligue 1 club believe they had no choice other than to ask FIFA to intervene.

Air accident investigators say the plane carrying Sala was not licensed for commercial use by authorities. The full findings of the investigation could take more than a year to be released.