Iran has arrested another Iranian-American, adding to a number of dual nationals the country has detained in recent years.

The Iranian-American was arrested in Gorgan, a city 250 miles northeast of Tehran, Iranian judiciary spokesman Gholam Hossein Mohseni Ejehi said during a press conference broadcast by state media.

Reports appeared last week that Robin Shahini, an Iranian-American man from San Diego, had been detained in Gorgan. While the location and timing matched, the judiciary spokesman didn’t name Mr. Shahini as the person arrested. Mr. Mohseni-Ejehi said he wasn’t aware of the charges against the Iranian-American.

U.S. State Department spokesman John Kirby said Thursday that he had seen reports on the case and that officials were looking into them, but he couldn’t comment further.

Iran’s Revolutionary Guards, a powerful force that answers only to ultraconservative Supreme Leader Ayatollah Ali Khamenei, have detained numerous dual nationals in recent years, in some cases charging them with spying and working to undermine the Iranian system. Iran doesn’t recognize dual nationality and considers people with multiple passports Iranians only.