Updated

A Washington-based lawyer says an Iranian-American businessman and his father, who are serving 10-year prison sentences in Iran, have lost their appeal.

Jared Genser said Monday that Baquer and Siamak Namazi learned the day before that the Tehran Appeals Court denied their request. Iranian officials and state media did not immediately report the failed appeal.

Siamak Namazi, a businessman, was arrested in October 2015.

His 81-year-old father Baquer is a former UNICEF representative who served as governor of Iran's oil-rich Khuzestan province under the U.S.-backed shah. He was arrested in February 2016, apparently drawn to Iran over fears about his incarcerated son.

The Namazis are among a number of dual nationals held in Iran after the 2015 nuclear deal. Analysts believe hard-liners use such detainees to undermine moderates.