• Nantes have demanded first of three payments for player • Cardiff want to wait until investigation into crash is complete

Nantes are set to take their dispute with Cardiff City over the death of Emiliano Sala to Fifa this week if the Premier League club fail to comply with the French club’s request for payment of the first instalment of his £15m transfer fee by Wednesday, it is understood.

The Argentinian striker died when a Piper Malibu plane – piloted by David Ibbotson, who remains missing – crashed into the English Channel on 21 January, two days after Sala signed for Cardiff from the French club.

Emiliano Sala died from head and trunk injuries, inquest hears Read more

Officials from both clubs, including the Cardiff manager Neil Warnock, attended his funeral in Argentina on Saturday but they have been at odds behind the scenes in a row that is threatening to overshadow what has been a dignified and united response to the tragedy.

Nantes’ lawyers wrote to the Premier League side on 5 February asking for the first of three annual payments for the player, as was agreed last month, to be paid within 10 working days.

Cardiff, however, have made it clear they want to wait until the investigation into the crash is complete, as there are several questions still to be answered about the accident, most notably if Ibbotson was qualified to be flying with a paying customer in that particular plane.

Any wrongdoing in regard to the flight could annul the Welsh club’s reported £16m insurance policy for Sala and, if that wrongdoing was another party’s responsibility, they may have to sue for compensation.

Nantes are eager to find a replacement for Sala, their leading scorer for the last three seasons, a situation further complicated by them owing Bordeaux 50% of the fee because of a sell-on clause agreed when they bought him in 2015.

Play Video 1:53 'The whole village is united': Warnock attends Emiliano Sala's funeral – video

There are further complications related to the number of agents involved in the deal, particularly the role played by Willie McKay, who obtained the mandate from Nantes to sell Sala to a Premier League club.

McKay has said he believes Cardiff are “trying to throw him under the bus” for Sala’s death and claims the club are not being honest about what they knew of his close involvement in the transfer. He claims he personally paid for six similar flights to help get the deal over the line, including two for Warnock to scout the player in France and Sala’s flights to visit Cardiff for the first time and then to return to Wales to sign his contract. Cardiff have yet to respond to requests for comment on his claims.

McKay also confirmed he was aware of Nantes’ intention to escalate their pursuit of the transfer fee by taking their case to Fifa, where the most likely response will be to send the matter to its dispute resolution chamber. Its chairman is the former Football Association chairman and Fifa vice-president Geoff Thompson.

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With the losing party, however, likely to be aggrieved, it is possible both sides would agree to skip a stage in the process and go straight to the court of arbitration for sport in Lausanne.