Family says Iran arrests father of US prisoner

Iranian security officials have arrested the 80-year-old father of an Iranian-American man already held for months without charge, his wife said on Wednesday.

In a Facebook post, Effie Namazi said her husband Baquer Namazi had been detained on Monday in Tehran and taken to the capital's notorious Evin prison.

"Now both my innocent son Siamak and my Baquer are in prison for no reason. This is a nightmare I can't describe," she wrote.

Baquer and Effie's son, Iranian-American citizen Siamak Namazi, was arrested last year. 

No charges have been announced and Namazi was not among several US citizens freed last month when Iran and the United States implemented a deal to curtail Tehran's nuclear programme in exchange for sanctions relief. 

"I have been trying to find out more information but have been unable to do so and the lawyer also couldn't get any information or get to see him," Effie Namazi wrote.

"I am extremely concerned and worried sick for Baquer's health since he is an 80-year-old man and has serious heart and other conditions which require him to take special heart and other medicine."

Spokesman Mark Toner said the US State Department was "aware of reports that a US citizen was detained in Iran" but that he could not give further details because of privacy laws.