MADRID (AFP) - Brazilian investment group DIS, which owned 40 per cent of Barcelona star Neymar's sporting rights before his move to the Catalan giants from Santos in 2013, claimed on Thursday that they felt "betrayed" after being shut out of the transfer negotiations.

Neymar, his father, Barcelona president Josep Maria Bartomeu and former club president Sandro Rosell were all called to testify by Spain's highest court this week over a complaint for fraud and corruption brought by DIS.

"I feel morally and economically betrayed," DIS owner Delcir Sonda told a press conference in Madrid.

The deal was originally valued at €57.1 million (S$89.6 million) by Barca, €40 million of which was paid to the N&N company owned by the player's father, with Santos receiving just €17.1 million.

However, the Spanish judicial authorities have estimated the number of simultaneous deals in the transfer amounted to at least €83.3 million.

DIS has claimed it was cheated of its real share of the benefits of the 23-year-old's move firstly because part of the transfer fee was concealed by Barcelona and Santos.

Moreover, they also believe a pre-contract agreement between Neymar and Barca impeded other clubs from making offers for the player affecting the value of the transfer fee.

DIS received just €6.8 million from the deal - 40 per cent of the amount paid to Santos.

"I feel the like the victim of a robbery," added Sonda, who invested €2 million for his share in Neymar's rights when he was just a promising talent in Brazil.

Football's governing body Fifa has tried to prevent similar cases by banning the third-party ownership system, commonly used in South America, whereby investors buy shares in promising players in the hope of a windfall when they move to European clubs.

"We still don't know what the real cost of the transfer was," said Jose Barral, general director of the Sonda group.

"Delcir only began to know about the transaction through the press. Santos, Barcelona and Neymar never contacted him about the subject. He had a share in the deal and was left without knowing what had happened."

Neymar claimed when he appeared before Spain's National Court on Tuesday that he was unaware of the fine details of the contracts his father had negotiated for him to sign.

The player's father also exonerated his son, but insisted there was nothing illegal in the way the deal was done.