The UN nuclear watchdog's board of governors has passed a resolution criticising Iran's lack of cooperation with the agency, diplomats told AFP on Wednesday, a decision Tehran slammed as "hasty and unwise".
The motion brought by Britain, France and Germany -- but opposed by China and Russia -- at the International Atomic Energy Agency's 35-nation board is the first of its kind since November 2022.
It comes amid an impasse over Iran's escalating nuclear activities and as Western powers fear Tehran may be seeking to develop a nuclear weapon, a claim Iran denies.
The resolution was carried by 20 votes in favour -- including the United States, which initially was reluctant for fear of aggravating Middle East tensions -- with 12 abstentions and one country not participating, three diplomats told AFP.
The confidential document obtained by AFP reiterates it is "essential and urgent" that Tehran provide "technically credible explanations" for the presence of uranium particles found at two undeclared locations in Iran.
"A continued failure" by Iran to provide full cooperation on the years-long probe "may necessitate" a comprehensive assessment by IAEA chief Rafael Grossi, the text said.
The resolution also says Iran must "reverse its withdrawal of the designations of several experienced Agency inspectors", and "without delay" reconnect the cameras used to monitor its nuclear activities.
The text also notes the "concerns" surrounding "recent public statements made in Iran... regarding its technical capabilities to produce nuclear weapons and possible changes to Iran's nuclear doctrine".
Following intense negotiations with the United States, the resolution was modified to secure Washington's support.
Although symbolic in nature at this stage, the censure motion aims to raise diplomatic pressure on Iran, with the option to potentially refer the issue to the UN Security Council.
Iran's mission to the United Nations said the censure motion was "hasty and unwise" and would "undoubtedly have a destructive effect on the process of diplomatic interaction and constructive cooperation", ISNA news agency quoted it as telling the Al-Monitor news website.
Tehran had already threatened "a serious and effective response" and called the censure motion "devoid of any legal, technical and political basis".
In the past, similar resolutions have prompted Tehran to retaliate by removing surveillance cameras and other equipment from its nuclear facilities and ratcheting up its uranium enrichment activities.
The IAEA has said that Tehran has significantly ramped up its nuclear programme and now has enough material to build several atomic bombs.
During the debates at the IAEA Board of Governors that began on Monday in Vienna, European powers denounced Iran's expansion of its nuclear programme "to alarming levels" as "unprecedented for a state without a nuclear weapons programme".
According to the IAEA, Iran is the only non-nuclear weapon state to enrich uranium to the high level of 60 percent -- just short of weapons-grade -- while it keeps accumulating large uranium stockpiles.
The resolution sent "a strong and renewed message of support" for the IAEA's efforts to address the issue, Britain, France and Germany, known as the E3, said in a separate statement.
"The Board will not sit idly by when Iran challenges the foundations of the non-proliferation system and undermines the credibility of the international safeguards regime," they added.
"We hope Iran takes this opportunity to resolve these outstanding matters so that no further Board action is necessary."
Iran has gradually broken away from its commitments under the nuclear deal it struck with world powers in 2015.
The landmark deal provided Iran with relief from Western sanctions in exchange for curbs on its atomic programme, but it fell apart after the unilateral withdrawal of the United States under then-president Donald Trump in 2018.
Efforts to revive the deal have so far failed.
In a joint statement quoted Wednesday by Iran's official news agency IRNA, Tehran, Moscow and Beijing called on "Western countries to show political will... and take the necessary steps to resume the implementation" of the 2015 deal.
But the United States rejected that assertion, saying Iran refused an accord when it was possible and "continued with activities that negated the chance for that deal, and now makes baseless statements to obfuscate the history".