Nantes have made a claim against Cardiff City in connection with the transfer of Emiliano Sala to the Premier League club, FIFA has confirmed.
Sala became Cardiff's record signing when he joined the Premier League club for a reported £15million in January, but the striker died in a plane crash before making an appearance.
Cardiff chairman Mehmet Dalman has promised the club will be "honourable" over the deal, but also said they want to investigate "anomalies" in the transfer before making a payment.
Neil Warnock confirmed Cardiff had been given an extension for the first instalment of the transfer fee last Thursday, but Nantes have since taken the matter to the world's governing body.
A FIFA spokesperson told Omnisport: "We can confirm that we have received yesterday [Tuesday] evening a claim of a contractual nature 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."