Two men suspected of being involved in a plot to kidnap a famous Brazilian judge have been killed in prison.

Janeferson Aparecido Mariano Gomes, better known as Nefo, and Reginaldo Oliveira de Sousa, known as Rê, were murdered by fellow inmates in a prison in São Paulo state, were they were being held in pre-trial detention.

They were arrested last year as part of a police operation dubbed Henchman, which uncovered a plan to kidnap high-ranking public figures for ransom.

Among those targeted was Senator Sergio Moro, a former public prosecutor who oversaw a huge corruption probe known as Operation Car Wash.

Nefo and Rê, who were both 48 years old, were attacked while on a "sunbathing break" inside the prison compound, according to CNN Brasil.

Nefo was stabbed to death in the toilets and Rê was killed in the courtyard, the news site reports.

Three inmates confessed to the crime and handed themselves in to the prison authorities.

They told officials they had killed the men in a "settling of scores".

Both victims and their attackers are suspected of belonging to the First Capital Command (PCC), Brazil's most powerful criminal group.

Brazilian news site UOL reports that the order to kill the two men would have come from "high up" in the PCC.

According to UOL, Nefo and Rê were targeted because they had "said too much".

They were detained in March 2023 when police uncovered the PCC's plan to kidnap Sergio Moro.

Officials think he was singled out by the criminal group because, during his time as Brazil's justice and security minister, he ordered that high-ranking members of the gang be transferred from smaller penitentiaries that they controlled to maximum-security jails.