Updated

Two Iranian-Americans jailed in Iran have lost an appeal over their 10-year sentences, Iran and the men's lawyer have said.

Baquer Namazi, 81, and his son Siamak, an Iranian-American businessman, lost their appeals, according to a Tehran prosecutor, as cited by a semi-official Iranian news agency.

Both men suffer from health problems related to their incarceration at Tehran’s Evin prison, which holds political detainees, Washington-based lawyer Jared Genser said.

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Siamak has spent much of his time in solitary confinement and “has been interrogated relentlessly, beated and tased,” according to Genser.

The Namazi family fled Iran after the 1979 Iranian Revolution. Siamak traveled back a number of times. He called for improved ties between Iran and the U.S., and urged Iranian-Americans to act as a bridge between the two governments.

It was his calls for an improved relationship that set off suspicion among hard-liners in Iran. Siamak was accused by an Iranian website in May 2015 of taking part in a Western effort to infiltrate Iran.

Siamak was arrested in October 2015, and his father, a former UNICEF representative, and former governor of Iran’s oil-rich Khuzestan province, was arrested in February 2016.

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Iran does not recognize dual nationalities, therefore detainees cannot receive consular assistance. In most cases, dual nationals face secret charges in closed-door hearings in Iran's Revolutionary Court, which handles cases involving alleged attempts to overthrow the government.

In October, authorities said the Namazis had been sentenced to 10 years in prison for "cooperating with the hostile American government."

The Namazis are among several dual nationals with Western ties being held in Iran after the 2015 nuclear deal.

The Associated Press contributed to this report.