"The text was submitted overnight" from Monday to Tuesday, a European diplomat told AFP. A second diplomat confirmed the news.

The resolution urging Iran to cooperate fully with the International Atomic Energy Agency (IAEA) marks the first time since June 2020 when a similar motion censuring Iran was adopted.

It is a sign of growing Western impatience after talks to revive the 2015 landmark nuclear accord with Iran stalled in March.

The vote is likely to happen on Thursday during the week-long meeting of the IAEA's 35-member Board of Governors, one of the diplomats said.

In a report late last month, the IAEA said it still had questions that were "not clarified" regarding traces of enriched uranium previously found at three sites, which Iran had not declared as having hosted nuclear activities.

IAEA head Rafael Grossi told reporters on Monday after opening the board meeting that he hoped "to solve these things once and for all".

The negotiations to revive the accord started in April 2021 with the aim of bringing the United States back into the deal, lifting sanctions and getting Iran to scale back its stepped-up nuclear programme.

The deal -- promising Tehran sanctions relief in exchange for curbs in its nuclear programme -- started to fall apart in 2018 when the then US president Donald Trump withdrew from it.

Iranian foreign ministry spokesman Saeed Khatibzadeh told state TV on Monday that Iran would reject the resolution, saying it would have "a negative impact both on the general direction of our cooperation with the IAEA and on our negotiations".

China and Russia -- who with Britain, France and Germany are parties to the Iran nuclear deal -- have warned that any resolution could disrupt the negotiation process.

"Russia will not associate itself with such a resolution," Russia's ambassador to the UN in Vienna, Mikhail Ulyanov, said in a tweet late Monday.

Analysts say the high stakes negotiations are unlikely to fall apart because of the resolution.