U.N. special envoy on human rights in Iran Ahmed Shaheed told the U.N. Human Rights Council that the situation in Iran was a mounting concern.
"There has been an apparent increase in the degree of seriousness of human rights violations in the Islamic Republic of Iran," he said.
He expressed concern over the government's restrictions on the right to freedom of expression and public assembly. Shaheed called on the government to uphold its international obligations and protect civil and political rights.
"Such rights are essential components of democracy and are all the more relevant in the context of Iran's upcoming presidential elections," he said in a statement. "Restriction(s) on freedom of expression and of association could potentially undermine the inclusiveness and fairness of the presidential elections."
A contested claim to victory in 2009 by Iranian President Mahmoud Ahmadinejad sparked violence in Iran not seen since the Islamic Revolution in 1979.
In February, Iranian Intelligence Minister Heidar Moslehi said his agency was watching for signs of subversion ahead of the June vote. Iranian Supreme Leader Ali Khamenei has warned that Iran's adversaries may try to undermine the vote.