Cardiff said on Wednesday they would appeal to the Court of Arbitration for Sport against FIFA's decision to make them pay Nantes the first instalment of the transfer fee for Emiliano Sala.

The world governing body this week ordered Cardiff to pay French club Nantes an initial six million euros ($6.5 million) in their dispute over the payment of the transfer fee for Sala, who died in a plane crash.

"There remains clear evidence that the transfer agreement was never completed in accordance with multiple contractual requirements which were requested by Nantes, thereby rendering it null and void," Cardiff said in a statement.

"We shall be appealing to CAS in order to seek a decision which considers all of the relevant contractual information and provides clarity on the full legal situation between our two clubs."