Secretary of State John Kerry says he is aware of reports that Iran has detained the father of an American man who was arrested by Iranian authorities last year.
The wife of Baquer Namazi says authorities in Tehran arrested her 80-year-old husband on Monday and may have taken him to the Evin prison.
In a Facebook post, Effie Namazi said she has been trying to get information concerning the arrest of her husband, who she said has a heart condition and other ailments.
In October, Iranian authorities arrested her son, Siamak Namazi, on unspecified charges. Both men have dual citizenship.
"Now both my innocent son Siamak and my Baquer are in prison for no reason," said Effie Namazi on Facebook.
Kerry was asked about Baquer Namazi's arrest during a Wednesday hearing in the Senate.
"I am very familiar with this and I am engaged on it specifically," Kerry said. "I am not permitted, due to privacy reasons, to go into details here."
In a statement, State Department spokesman Mark Toner said the agency had "no higher priority than the protection of U.S. citizens overseas."
In January, Iran released five detained Americans in a complex swap that was finalized right before the implementation of the Iran nuclear deal.