An Iranian-American businessman has been detained by authorities in Iran, reports say.
Siamak Namazi was held earlier this month while on a visit to Tehran, a family friend told the Washington Post.
He was detained by intelligence agents and is being kept in solitary confinement in Evin prison, the Reuters news agency quoted a source saying.
If confirmed, it will be latest in a number of detentions of Iranian-American citizens in the country.
The US state department said it was looking into the reports of Mr Namazi’s arrest. It comes despite a thawing in relations between Iran and the West – including a deal on the country’s nuclear programme.
Iran is also attending talks on the Syrian civil war for the first time this week.
Mr Namazi – who reportedly lives in Dubai and works for a oil and gas company in the United Arab Emirates – was barred from leaving the country in July, Reuters says.
He was questioned regularly before being detained in mid-October, the source added.
It is unclear what charges, if any, he faces.
Earlier incidents involving Iranian-Americans in Iran include the detention of Washington Post reporter Jason Rezaian, 39.
He was held in custody for more than a year on accusations that have been denied by the newspaper.
Earlier this month, a verdict was issued on charges including espionage, Iran’s judiciary said. Officials did not give details of the judgement, but hinted at a conviction.
Saeed Abedini was jailed in 2012 after being accused of setting up a Christian prayer network in private homes.
And Amir Mirzai Hekmati was accused of being a CIA spy, a charge US Secretary of State John Kerry has said is false.
Mr Kerry has called for the men, both of whom are dual citizens, to be released.