A Lebanese-born technology expert whose group has a Washington branch has been arrested in Iran and accused of links to the U.S. military and intelligence agencies, Iranian state TV reported Tuesday.

The announcement was the first word from Iran on Nizar Ahmad Zakka, whose colleagues said he did not board a scheduled flight from Tehran on Sept. 18 after attending a conference.

The reported arrest is the latest in recent weeks to target a visitor with U.S. ties. A Dubai-based businessman with dual U.S.-Iranian citizenship, Siamak Namazi, was detained in early October on charges that have not been made public, according to a family member.

The Arab ICT Organization, also known as IJMA3, where Zakka serves as secretary general, said in a statement Monday that Zakka was in Tehran at the invitation of the Iranian government to attend a conference on “women and sustainable development.”

It said Zakka, 49, last made contact before leaving his hotel for Tehran’s airport to board a flight to Beirut.

Iran’s state-run IRIB channel provided no specifics about the allegations against Zakka but quoted an unnamed official as saying that Zakka “has deep ties to the U.S. intelligence and military establishment,” the Reuters news agency reported.

Zakka’s organization, an information and communications technology group that has offices in Lebanon, Iraq and Washington, did not immediately respond to inquiries seeking comment.

His Beirut-based attorney, Antoine Abu Dib, said Zakka is not an American citizen but spends much of his time in the United States. Abu Dib declined to give details, pending a statement from Zakka’s family. He said he had no official information on Zakka’s reported arrest or whereabouts.

Zakka’s Internet profile said he is based in Washington. IJMA3 said it seeks to promote and develop Web-based technology and access across the Middle East and North Africa.

Iran holds at least three other Americans, including Washington Post journalist Jason Rezaian , who was convicted last month on espionage and other charges after a closed-door trial. Rezaian’s family and attorney strongly deny the charges.

Others in custody are retired Marine Amir Hekmati of Flint, Mich., who was accused of being a spy when he went to Iran to visit his grandmother and has been held since 2011; and Saeed Abedini, a pastor from Boise, Idaho, who was convicted in 2013 of threatening Iran’s national security by participating in home churches. Both deny the charges.

Hugh Naylor and Suzan Haidamous in Beirut and Craig Whitlock in Washington contributed to this report.

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