Santos had presented a claim to soccer's world governing body FIFA in 2015 asking for $61.3 million ($A99.5m) in compensation and damages after Barca made a payment to Neymar's father and the family company N&N before signing the Brazil forward for an initial fee of 57m euros ($A92.5m).

"The CAS found that the contract between Santos and Neymar was ended by mutual agreement and that Barcelona did not flout the transfer agreement when it paid additional fees to the player's father and the firm N&N," Barca said.

"Barcelona did not commit any fraudulent conduct when it signed a pre-transfer agreement with Neymar nor when it signed the transfer with Santos."

The statement added that Santos had been ordered by CAS to pay Barca's legal fees of 20,000 Swiss Francs ($30,500).

Santos released a statement saying they "regret but respect the decision", adding that the club was "undeniably hurt by the transfer".

Neymar's transfer from his boyhood club to Barcelona was shrouded in legal troubles, leading Spain's High Court to launch a fraud and corruption investigation into the player, who denied any wrongdoing, over the value of his transfer.

The investigation also led to Barca's then president Sandro Rosell, who brokered the deal, resigning in 2014.

Neymar enjoyed a trophy-laden four years at Barcelona and formed a world-beating front three with Lionel Messi and Luis Suarez before joining Paris Saint-Germain in 2017 for a world record fee of 222m euros ($A360m).

Neymar then sued Barca over the partial payment of a loyalty bonus worth 26m euros ($A42.2m) but lost the case and was ordered to pay his former club 6.7m euros ($A10.9m) for breach of the last contract he signed with them in 2016.

Despite their legal battles, a return to thre Catalan giants of the Brazilian star has long been mooted.

Australian Associated Press