Iranian American consultant Siamak Namazi in Berlin in 2015. (Courtesy of Ahmad Kiarostami/via Reuters)

The Iranian judiciary has indicted three dual-national prisoners, including an American businessman, and a Lebanese citizen who is working on contract for the U.S. State Department, Iranian news agencies reported Monday.

The indictments were handed down sometime in the past two weeks, but the exact nature of the charges was not immediately disclosed. Earlier this year, a spokesman for the judiciary said most of the dual nationals — detained while visiting the country for personal or professional reasons — were suspected of some form of espionage.

Also charged was a British charity worker and a Canadian academic. All four were arrested by the Iranian Revolutionary Guard Corps, a hard-line group that has consistently opposed the opening to the West epitomized by the nuclear deal reached a year ago.

The case of Siamak Namazi has drawn the most attention in the United States. An Iranian American businessmen who spoke out often over the years against sanctions on Iran, he was arrested in October on a trip to promote business between the two countries. His father, Baquer Namazi, was arrested in February when he came to Iran to try to get his son released. He has not been indicted.

Siamak Namazi’s attorney told the Iranian news agency Tasnim that his client has been charged with working with a hostile government — the United States.

Namazi’s fate is often cited by Iranian Americans who say they are afraid to return to the country where they were born. Iran does not recognize dual nationality, so dual nationals are treated as Iranian citizens and are not entitled to consular visits, such as from the Swiss Embassy, which represents U.S. interests in Iran.

“The continued detention of Baquer and Siamak Namazi, as well as other dual nationals, is unjust and very poisonous for Iran’s relations with the Iranian diaspora and with Western countries,” Bijan Khajehpour, a former business partner of Siamak Namazi, said Monday.

Nazanin Zaghari-Ratcliffe, a program coordinator with the charitable Thomson Reuters Foundation, is the dual-national Iranian British citizen being held.

“Nazanin is being held because she has a British passport — her work for British charities and links to the outside [are] being used as a bogeyman in Iranian domestic politics, and her passport makes her a bargaining chip for international negotiations,” said Richard Ratcliffe, her husband. “It is precisely because she is British dual national that she has been taken as collateral by Iran.”

The detained Canadian is Homa Hoodfar, a dual-national professor at Concordia University in Montreal who was arrested in March as she was preparing to return to Canada. She is an anthropologist who specializes in gender and sexuality in Islam.

Iran also indicted Nizar Zakka, a Lebanese citizen who is a U.S. resident living in the Washington area. He is an information technology specialist who was in Tehran attending a conference at the invitation of an Iranian vice president when he was arrested in September.

“I’m very disappointed to hear the news about an indictment,” said David Ramadan, a former Virginia state legislator who is a friend. “Nizar is not involved in any anti-Iranian activities, and therefore these accusations are null.”

Ramadan called on Secretary of State John F. Kerry to get involved in negotiating Zakka’s release.

Haleh Esfandiari, an Iranian scholar at the Washington-based Wilson Center who was once imprisoned in Iran, said the Revolutionary Guard has been under considerable pressure to release the dual nationals, and the indictments could be their response.

Alternatively, Iran may want a prisoner swap, she said, like the one in January that led to the release of Washington Post reporter Jason Rezaian and four other U.S. citizens.