Monday marks the second anniversary of the house arrest of Iranian opposition leaders Mehdi Karroubi and former Prime Minister Mir Hossein Mousavi. Mousavi's loss to Iranian President Mahmoud Ahmadinejad in 2009 sparked unrest in Iran not seen since the Islamic Revolution in 1979.
Ahmed Shaheed, U.N. special on the human rights situation in Iran, expressed concern about the continued isolation of Iranian opposition leaders.
"Continued restrictions of this kind will undermine the inclusiveness and fairness of the future presidential election," he said in a statement from Geneva.
"I call on the government to facilitate a transparent and open environment for the election by releasing opposition leaders and allowing the media to effectively and independently report, without being harassed, threatened or arrested."
Iran is to have presidential elections in April. Ahmadinejad is ineligible to compete because of term limits. Also, since his re-election, he's fallen out of favor with Iran's clerical elite.
Mousavi's daughters, Zahra and Nargis, were arrested Monday after protesting the house arrest of their father and his wife, Zahra Rahnavard.