* Namazi being held in solitary confinement - source
* Namazi detained while in Iran to visit family
* Four Iranian-Americans now detained in Iran (Changes sourcing, adds detail on arrest and detention)
WASHINGTON, Oct 30 (Reuters) - A prominent Iranian-American businessman has been detained by authorities in Iran, potentially throwing up another obstacle to closer U.S.-Iran ties in the wake of the nuclear deal between the countries.
Siamak Namazi was detained by Iranian authorities in mid-October, according to a source briefed on the matter who requested anonymity. He had been traveling in Iran, where his parents live, to visit family and was barred from leaving the country in July, the source said.
The source said Namazi had not been in Iran on business.
Namazi was detained by the intelligence service of Iran’s Islamic Revolutionary Guard Corps and is currently being held in solitary confinement in Evin prison, the source told Reuters.
Namazi had been regularly called in for interrogation between July and the time he was detained, the source also disclosed.
“We’re aware of recent reports of the possible arrest in Iran of a U.S. citizen,” a senior Obama administration official said. “We’re looking into these reports and don’t have anything further to provide at this time.”
Namazi lives in Dubai and works as the head of strategic planning for Crescent Petroleum, an oil and gas company in the United Arab Emirates. He previously was chief executive of Atieh Bahar Consulting, a private marketing and strategic consulting firm in Iran.
Namazi, well known among Iran policy experts, attended university in the United States and the United Kingdom and previously worked at think tanks and institutions in Washington, D.C. In 2007, he was chosen as a “Young Global Leader” by the World Economic Forum.
Namazi’s career has revolved to a great extent around the changing business and diplomatic ties between the United States and Iran. In 2013, he wrote an editorial in the New York Times criticizing U.S. and European sanctions for blocking the import of critical medicines into Iran.
His arrest makes him the fourth Iranian-American currently detained in Iran. An reporter for the Washington Post, Jason Rezaian, was convicted this month after being arrested in July 2014 and accused of espionage. Amir Hekmati, a former U.S. Marine, was jailed by Iran on spying charges in 2011. And Saeed Abedini, an Iranian-American Christian pastor, was sentenced to eight years in jail in 2013.
The detentions have been an obstacle to thawing U.S.-Iran relations, which improved during the negotiation of a historic July nuclear deal. Iran agreed with world powers to limit its nuclear program in return for the lifting of sanctions.
The Wall Street Journal, which earlier reported the news of Namazi’s arrest, said that in recent weeks Iranian business officials with ties to foreign companies had been held, interrogated and warned against wading into economic monopolies controlled by the Revolutionary Guard.
Friends of Namazi told the Journal that Iranian intelligence agents had ransacked his family home, seized his computer and then conducted cyber attacks on some of his email contacts.
Earlier this month, Secretary of State John Kerry defended the U.S. decision not to make the release of Iranian-Americans a condition for the nuclear agreement with Iran, but he called on Iran to release the men and drop all charges against them.
The deal is favored by more moderate factions in Iran but is opposed by hardliners, who control Iran’s judiciary and security apparatus and are seen by Iran experts as being behind the detentions. (Reporting by Washington bureau; Editing by Mark Bendeich)