(Adds details on arrest, background; U.S. official's comment)
WASHINGTON, Oct 29 (Reuters) - An Iranian-American businessman was arrested by Iranian security forces two weeks while he was visiting relatives in Tehran from his home base in Dubai, the Wall Street Journal reported on Thursday.
The newspaper, citing people briefed on the situation, said Siamak Namazi, head of strategic planning at Crescent Petroleum Co, was arrested by the Revolutionary Guard's intelligence arm, which reports to Supreme Leader Ayatollah Ali Khamenei.
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, the Journal said, quoting several businessman interviewed inside and outside Iran.
A senior official in U.S. President Barack Obama's administration told Reuters: "We're aware of recent reports of the possible arrest in Iran of a U.S. citizen. We're looking into these reports and don't have anything further to provide at this time."
The report comes as Washington has urged Tehran to free three other Americans it is holding, including Washington Post reporter Jason Rezaian and to help find Robert Levinson, an American who disappeared in Iran eight years ago.
Despite Washington's long-standing contentious relationship with Tehran, the United States and other major powers forged a deal in July with Iran to curb its nuclear program in return for relief from sanctions.
Friends of Namazi told the newspaper that his family home was ransacked by Iranian intelligence agents, who confiscated his computer and had since conducted cyber attacks on some of his email contacts.
Namazi has been living in recent years in Dubai while working for Crescent Petroleum, sources familiar with his situation told the Journal. He went to Tehran three months ago to visit relatives.
Namazi's friends said Iranian security agents confiscated his Iranian passport and prevented him from leaving the country, the Journal reported. They said he was being held in Tehran's Evin prison, which is where political opponents of the government are kept.
The Journal said Namazi had strongly supported the nuclear accord with Tehran and the lifting of international sanctions, which he had argued disproportionately hurt average Iranians.
Namazi's family owns Atieh Group, a conglomerate with offices in Tehran, Dubai and Vienna that includes consultancies that advise foreign companies about entering the Iranian market, the Journal said.
(Reporting by Peter Cooney; Editing by Eric Beech) ((peter.cooney@thomsonreuters.com; +1-202-898-8322; Reuters Messaging: peter.cooney.thomsonreuters.com@thomsonreuters.net))
Keywords: IRAN USA/ARREST
