The father of a detained Iranian nuclear scientist says he fears for his son's safety.
Asgar Amiri told the BBC Persian service that he has not been allowed to see or speak to his son, Shahram, for more than a year.
He said his son, who is being held at a secret location, "did not look well" when he last saw him last September.
Shahram Amiri, who is in his 30s, went missing in Saudi Arabia in 2009 and resurfaced in the United States the following year.
In a series of video recordings, he first claimed he had been kidnapped by U.S. and Saudi agents, then he said he was living freely in the United States, and finally he announced that he wanted to go home.
Amiri returned from the United States in July 2010, reuniting with his wife and son.
He was later reported to have been sentenced to prison.
Based on reporting by the BBC