Judicial agents are accusing an inmate in a medium security section of La Reforma prison of making at least 17 sexy calls to youngsters.
The agents entered the prison Wenesday and said they found cell telephones and other evidence, including telephone numbers.
The 56-year-old suspect had been jailed for similar crimes, said agents.
The man is accused of making telephone calls to minor girls and engaging them in increasingly sexy conversations involving body parts and underclothes, said the Judicial Investigating Organization.
Investigators are seeking to have the man remanded to maximum security, they said.