The board of governors of the United Nations’ atomic agency issued a resolution on June 19 urging Iran to provide access to two sites where nuclear activity may have occurred in the past.
It is the first resolution of its kind since 2012.
The resolution calls on Iran to "fully cooperate” with the International Atomic Energy Agency (IAEA) and “satisfy the Agency's requests without any further delay,” including by providing “prompt” access to the two sites in order to clarify whether undeclared nuclear activity took place there during the early 2000s.
Iran has been blocking access to the sites for months, prompting a growing diplomatic dispute.
The resolution was passed by 25 votes in favor of the resolution -- which was put forward by France, Germany, and Britain with support by the United States.
Russia and China voted against while seven countries abstained -- Azerbaijan, Pakistan, India, Mongolia, South Africa, Thailand, and Niger.
Kazem Gharib Abadi, the Iranian ambassador to the IAEA, said his country “strongly rejects this resolution and will respond appropriately in due course."
Iranian officials have said that such a resolution could hurt relations between Tehran and the UN agency.
Russia's ambassador to the UN in Vienna, Mikhail Ulyanov, tweeted that “the resolution can be counterproductive,” while also “stressing the need for Tehran and IAEA to settle this problem without delay.”
The sites in question are not thought to be directly relevant to Iran's current nuclear program. But the IAEA says it needs to know if activities going back almost two decades have been properly declared and whether all nuclear materials have been accounted for.
The IAEA says it still has the access it needs to inspect Iran's declared nuclear facilities according to its mandate under the landmark nuclear deal reached in 2015 between Iran and world powers.
The United States pulled out of the agreement in May 2018 and reimposed sanctions that have hurt the Iranian economy.
In response, Tehran has been progressively breaking the restrictions laid down in the agreement, saying that it can reverse them if the remaining parties to the deal -- Britain, France, Germany, China, and Russia -- comply with the deal. U.S. sanctions make it difficult for other parties to abide by their commitments.
The United States has also pushed for an extension of an arms embargo on Iran beyond October, when it was set to be progressively eased under the nuclear accord.
After meeting in Berlin on June 19, the foreign ministers of Britain, France, and Germany said that they too opposed lifting the embargo, saying that the move "would have major implications for regional security and stability."
But the ministers also said their countries would not back U.S. efforts to unilaterally trigger the reimposition of UN sanctions on Iran.
“Any unilateral attempt to trigger UN sanctions snapback would have serious adverse consequences in the UN Security Council," they said in a joint statement.
However, they added that they "wish to address the issue in close coordination with Russia and China."