Abdolfattah Soltani was sentenced to 18 years in prison on charges of distributing "propaganda against the state." In 2003, he helped set up the Center for Human Rights Defenders with Nobel Peace Prize laureate Shirin Ebadi.
He's to serve his term in "exile" at a prison in southern Iran because authorities, Human Rights Watch reported, said his presence at prisons in Tehran would "cause corruption."
"Soltani should not spend a minute, let alone 18 years, in a prison hundreds of miles away, for acts directly related to his exercise of basic human rights," Joe Stork, deputy Middle East director at Human Rights Watch, said in a statement from New York. "The appeals court should quash this unfair sentence and free him."
Several of Iran's opposition leaders, including former presidential candidates Mehdi Karroubi and Mir Hossein Mousavi, are in prison or house arrest on various anti-regime charges.
Iran had parliamentary elections last week, the first since Karroubi and Mousavi helped lead post-election demonstrations in 2009. Opponents of Iranian President Mahmoud Ahmadinejad were the most successful candidates in the election.