Cardiff City have been ordered by world soccer governing body FIFA to pay the second and third instalments of the transfer fee for Emiliano Sala to French side Nantes, the Championship club said on Friday.

Sala's plane crashed in the English Channel, killing him as well as the pilot, as the Argentine striker travelled to Cardiff after signing for 17 million euros ($18.55 million) from the Ligue 1 side in January 2019.

Cardiff were told by FIFA to pay the first instalment of the transfer fee agreed before Sala's death, which amounted to six million euros, but the club now want the next instalments deferred amid an investigation into the French club.

"Yesterday the CEO of FC Nantes, Franck Kita, was placed into police custody alongside [agents] Bakari Sanogo and Joaquim Batica by the JIRS, French prosecutors specialised in organised crime and financial crime," Cardiff said in a statement.

"The club's negligence claim in France against FC Nantes exhibits direct exchanges showing Mr Kita was informing Mr Sanogo of the proposed transfer fee for Emiliano Sala. It is not clear why.

"In the circumstances, the club considers that it would have been fairer if the requirement to pay Nantes had been deferred until the conclusion of the French police investigations and the club's claim against Nantes in the French courts."

In May, Cardiff said they were taking further legal action against Nantes after the Swiss Federal Tribunal decided the Court of Arbitration in Sport (CAS) had no jurisdiction to deal with their claim for damages over Sala's transfer.

In August last year, CAS had dismissed Cardiff's appeal against a FIFA decision ordering them to pay the first instalment of his transfer fee.

Cardiff were relegated at the end of the 2018-19 season after finishing 18th and have not gained promotion back to the top flight since.