BEIRUT (Reuters) - An Iranian-American detained in Iran since last summer has been released on bail of approximately $60,000, the Human Rights Activists News Agency (HRANA) reported Sunday.

Robin Reza Shahini was arrested by the Revolutionary Guards while visiting family in the northeastern city of Gorgan last July and subsequently sentenced to 18 years imprisonment on charges of threatening national security, according to HRANA.

Shahini went on a hunger strike for a month recently and his health situation had been deteriorating, the HRANA report said.

Two other Iranian-Americans are still being held in the Islamic Republic.

Iran’s Revolutionary Guards detained Siamak Namazi, a businessman in his mid-40s with dual U.S.-Iranian citizenship, in October 2015 while he was visiting family in Tehran.

The Guards arrested his 80-year-old father Baquer Namazi, a former Iranian provincial governor and former UNICEF official who also has dual citizenship, in February 2016.

Both men were sentenced to 10 years in prison for spying and cooperating with the United States government, Tehran prosecutor Abbas Jafari Dolatabadi said last October, according to the Fars news website. It did not specify when exactly the sentences had been handed down.

Another detainee is Iranian-British aid worker Nazanin Zaghari-Ratcliffe, who was sentenced to five years in prison last fall on charges that remain secret, according to her family.

The Revolutionary Guards have accused her of trying to overthrow Iran’s clerical establishment.

Zaghari-Ratcliffe works for the Thomson Reuters Foundation, a London-based charity that is independent of Thomson Reuters and operates independently of Reuters News. The Foundation and her husband have dismissed the Revolutionary Guards’ accusation.

The U.S. State Department issued a warning in March 2016 noting that Iranian-Americans are particularly at risk of being detained or imprisoned if they travel to Iran.

Shahini, in his mid-40s, graduated last spring from San Diego State University, where he studied international security and conflict resolution, his former classmate Jasmine Ljungberg told Reuters last year. He was set to start a master’s program in homeland security at the university last fall, she said.

The HRANA report did not indicate whether Shahini would be allowed to leave the Islamic Republic while out on bail.