Three men held for five months over a shocking underage sex abuse scandal in Argentine football have been released, one of the defendants said on Friday.

Referee Martin Bustos, football agent Alberto Ponte, and public relations agent Leonardo Cohen Arazi, all accused of grooming, were released after an appeals court in a southern Buenos Aires neighborhood changed the charges against them from sexual abuse to corruption of minors.

The latter offence carries a minimum penalty of three years but qualifies defendants for parole.

The charges came about after a 17-year-old player at Buenos Aires giants Independiente told a club psychologist he had been encouraged, alongside another 19-year-old player, to prostitute himself to adult men in a trendy Buenos Aires neighborhood.

Club bosses alerted judicial authorities and public prosecutor Maria Soledad Garibaldi launched an investigation into a suspected illicit underage sex network operating at one of Argentina's most illustrious clubs.

Garibaldi said trainee footballers housed at the club's boarding facility had been offered as little as a pair of boots or even just underwear in return for sex.

Four people remain in detention accused of sexual abuse and corruption of minors in a case involving 15 known victims.

Cohen Arazi's lawyer, Adrian Cornaglia told C5N television station that there was no evidence against his client, who was "unjustly detained for more than five months."

He added that Cohen Arazi had admitted to "paying for sex but that was never with a minor and if it was with a minor, he didn't know."

Back in March, Andres Bonicalzi, a lawyer for a rape victims charity, said many young players from the vast interior of Argentina were housed in boarding facilities far away at Buenos Aires clubs on the western shore of the Rio de la Plata estuary.

This made them particularly vulnerable to exploitation.

"They see the club as a role-model, they see it as a father-figure. They're far away from their own fathers," said Bonicalzi.

"(The perpetrators) have exploited their immaturity and these children's need to belong to something."

Garibaldi is planning on opening another case with a possible 20 victims housed at other clubs, including Lanus, Banfield, Temperley, Estudiantes and Gimnasia La Plata.

No club officials are suspected of involvement in any of the crimes.

A parallel investigation opened at the time of the Independiente one, involved another of Argentina's football giants, River Plate, also involving the sexual abuse of boys at a boarding facility.

But there has been no update on its progress since, nor that of a similar investigation involving the Argentine Gymnastics Federation.