The assembly's human rights committee approved a resolution calling on Iran to carry out reforms to curb abuses ranging from suppression of media to torture and discrimination against women and minorities.
The measure was approved yesterday by a vote of 69 to 55, with 51 abstentions. It is expected to be approved by the assembly next month.
Canada sponsored the resolution for the second year in a row. Its UN ambassador, Allan Rock, told the committee he hopes the measure will promote change in Iran.
"For those many who are denied the right to speak out, for those minorities who suffer persecution in silence, for women who face discrimination, hardships and sometimes physical harm, it is our desire to improve their lives that motivates this resolution," Rock said.
The resolution noted some positive developments, such as the visits to Iran of UN rapporteurs and human rights dialogues between Iran and a number of states. But Rock said the overall situation has deteriorated since last year and that it is important to bring the weight of international opinion to bear on Iran.
The resolution is not binding but carries symbolic importance.
Iranian envoy Paimaneh Hasteh called the resolution's charges baseless. She accused Canada of introducing the measure in response to a domestic outcry over the death in 2003 of Canadian photojournalist Zahra Kazemi while in custody in Iran.
An Iranian court this summer moved to end the trial of the key suspect in her death. That prompted an outcry from Canada and Kazemi's legal team, led by Nobel Peace laureate Shirin Ebadi.
Hasteh told the committee that Iran's judiciary continues to investigate the death. She cautioned that resolutions singling out Iran for reproach are doomed to fail.
"We even warn that this approach, if it continues to prevail, will jeopardize the entire processes of ongoing cooperation and dialogue initiated by the government of the Islamic Republic of Iran at the bilateral and multilateral levels," Hasteh said.
The vote followed a pattern familiar at UN human rights panels when single-country resolutions are proposed. European states, the United States, and Latin American nations supported the measure, while Islamic and developing states opposed it.
Opposing states said such "naming and shaming" resolutions are counterproductive and divisive for the committee.
Pakistani representative Billal Hayee, speaking on behalf of the Organization of the Islamic Conference, said the resolution will not serve to promote human rights.
"It increases the risk of generating confrontation and politicization at the international level on human rights issues by creating a gulf between the developed and the developing countries quite opposite to the very agenda of the United Nations," Hayee said.
Other states objecting to the practice included Turkmenistan and Belarus, which themselves face critical resolutions in the committee, and Sudan, subject to a UN investigation into whether genocide is being committed in the Darfur region.
But the Czech Republic's representative, Ivana Grollova, sought to stress the importance of such resolutions. She noted that 17 November was the 15th anniversary of events triggering the fall of communism in Czechoslovakia and the improvement of human rights.
"Please allow me today to express my honor that on behalf of my government I could today join those who care about the protection of the fundamental freedoms and human rights of everybody," Grollova said.
Forty countries co-sponsored the resolution, including the United States and 25 countries of the European Union. Countries voting against the measure included Russia, the five Central Asian states, Armenia, and Azerbaijan.