Iranian state television on Tuesday claimed that a Washington-based Lebanese citizen missing in Tehran since September is actually an American spy now in the custody of authorities.

The state TV report is the first official word about Nizar Zakka, who holds permanent-resident status in the U.S. It comes as four Americans are known to be held by Iranian authorities after the Islamic Republic struck a nuclear deal with world powers.

Zakka disappeared Sept. 18 while visiting Tehran for a state-sponsored conference, according to a statement from the Washington-based group IJMA3-USA, which advocates for Internet freedom across the Middle East. Zakka was last seen leaving his hotel in a taxi for the airport to fly to Beirut, but he never boarded his flight, according to a statement last week signed by Lebanese lawyer Antoine Abou Dib.

Reached Tuesday by The Associated Press, Abou Dib said he had not heard of the Iranian claim and declined to immediately comment. IJMA3-USA did not immediately return a request for comment. Lebanese officials couldn't be immediately reached for comment.

The state TV report claimed Zakka had "deep links" with U.S. intelligence services and its military. It also aired a still photo of men in U.S. Army-style uniforms, claiming Zakka was one of the men.

It wasn't immediately clear if Zakka ever served in a military. However, Riverside Military Academy of Gainesville, Georgia, lists Zakka as an alumnus on its website and describes him as "an internationally recognized expert in information and communications technology (ICT) policy." It said he graduated from the academy in 1985 and later earned bachelor's and master's degrees in computer science from the University of Texas.

A spokeswoman for Riverside Military Academy referred questions to Jim Benson, the school's president. He did not immediately respond to a request for comment.

Zakka's disappearance comes as hard-liners in Iran remain opposed to a detente with the U.S. in the wake of the nuclear deal. That agreement reached earlier this year promises lifting crippling economic sanctions in exchange for curbs on its nuclear program.

Iranian hard-liners are opposed to moderate President Hassan Rouhani's strategy of trying to improve ties with the West. Internal domestic struggles over the direction of Iran appear to be intensifying ahead of February's parliamentary elections.

There also may be another plan: in August, Iranian media began quoting officials discussing the possibility of swapping Americans detained in Iran for 19 Iranians held in the U.S. It's unclear, however, whether that's been seriously discussed between Iranian and U.S. officials.

Americans held in Iran include Washington Post journalist Jason Rezaian, an Iranian-American convicted of charges including espionage in a trial widely criticized by the Post and free press groups. Others include former U.S. Marine Amir Hekmati, who holds dual Iranian and American citizenship and was arrested in August 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.

The U.S. also says it has asked for the Iranian government's assistance in finding former FBI agent Robert Levinson, who vanished in 2007 while working for the CIA on an unapproved intelligence mission. Iran has said in the past that it has no information on Levinson, though it did not rule out helping in the case.