Mansur Osanlu, the jailed head of Tehran's bus drivers union, has been transferred to a prison section where drug addicts are kept, his mother has told RFE/RL's Radio Farda.
This is not Osanlu's first time in the section for drug addicts and prisoners suffering from hepatitis and AIDS. He was put in the same ward in March, before being returned to the regular prison.
Osanlu is being held at Gohardasht prison in Karaj, a suburb of Tehran.
Fateme Gol Gazi, Osanlu's mother, spoke to Radio Farda on May 30. Asked why her son had been transferred again to the section for drug addicts. Gol Gazi said, "The reason is that whenever foreign government officials and workers say that Osanlu is innocent and should be released, the next day they take him for trial and shift him from cell to cell."
Osanlu was arrested in July 2007 after being abducted on the street by security forces.
He is serving a five-year prison term for what the authorities say was acting against "national security." He had been detained several times between 2005 and 2007.
His mother complained that judicial officials have kept the family in the dark over Osanlu's legal situation.
"We have sent countless letters to different courts and officials," she said. "His wife and I are always wandering from court to court without receiving any proper response. They are putting pressure on us by not giving us any explanation. They are doing all this because they want to open a new case against my son."
Gol Gazi said she had not heard from her son since May 27. She also complained that it would be difficult for her to visit him.
"I am an old and sick mother," Gol Gazi said. "Should I wish to visit him in prison, I would have to arrive at five in the morning. Following a series of endless, frustrating procedures, I would return at six in the evening after a 15-minute meeting with my son."
Gol Gazi said Osanlu's wife and daughter-in-law have received telephone threats from the authorities.
"I implore them [authorities] to put an end to this if they are listening to me. What trial and what case do they want to make against him who is already serving a prison sentence. I want my child's freedom," she said.