Britain, France and Germany -- signatories to the Joint Comprehensive Plan of Action intended to stop Tehran obtaining nuclear weapons -- allege that Iran has broken its promises under that 2015 treaty.

Diplomatic sources expect that the resolution will not have the nine votes needed to uphold the status quo -- in which sanctions remain lifted -- and as such the punishment will be reimposed.

French President Emmanuel Macron said he expected international sanctions against Iran to be reinstated by the end of the month, in an excerpt from an Israeli television interview broadcast Thursday.

"The latest news we had from the Iranians are not serious," he said.

In a letter to the UN in mid-August, the "European Three" slammed Iran as having breached several JCPOA commitments, including building up a uranium stock to more than 40 times the level permitted under the deal.

Despite a flurry of diplomatic talks between the European powers and Tehran, the Western trio insisted there was no concrete progress.

Russia and China, which oppose the reinstatement of sanctions, would need to secure nine votes from the 15 members of the Council -- which diplomatic sources say may prove impossible.

"Algeria and Pakistan may support Russia and China in backing the resolution, but I think other members are likely to oppose it or abstain, so the Europeans and US will not have to use their veto," said International Crisis Group analyst Richard Gowan.

The vote could result in the imposition of sanctions as early as next week -- although the UN's annual high-level meeting which Iranian President Masoud Pezeshkian will attend could present opportunities for last-ditch negotiations.

"The Council still has time to greenlight a further resolution extending the suspension of sanctions -- if Iran and the Europeans reach a last-minute bargain," Gowan said.

- Last minute bargain? -

The hard-won 2015 deal has been left in tatters ever since the United States, during Donald Trump's first presidency, walked away from it in 2018 and reimposed sanctions on Iran.

Western powers and Israel have long accused Tehran of seeking to acquire nuclear weapons, a claim Iran denies.

Following the US withdrawal, Tehran gradually broke away from its commitments under the agreement and began stepping up its nuclear activities, with tensions high since the 12-day war between Iran and Israel in June.

The war also derailed Tehran's nuclear negotiations with the United States and prompted Iran to suspend cooperation with the IAEA, with inspectors of the Vienna-based UN body leaving the country shortly after.

During his previous term, Trump attempted to trigger the so-called "snapback clause" to reimpose sanctions in 2020, but failed due to his country's unilateral withdrawal two years earlier.

While European powers have for years launched repeated efforts to revive the 2015 deal through negotiations and said they "have unambiguous legal grounds" to trigger the clause, Iran does not share their view.

Iran has threatened to withdraw from the Nuclear Non-Proliferation Treaty (NPT) if the snapback is triggered.