France leads efforts urging Trump to save Iran deal

France is stepping up global efforts to convince US President Donald Trump not to scrap the Iran nuclear deal, suggesting ways to prolong the landmark agreement signed in 2015.

Iran, together with North Korea, will dominate the annual gathering of world leaders at the United Nations, which opens on Tuesday with a series of addresses by Trump and Macron, among others.

Iranian President Hassan Rouhani is scheduled to speak on Wednesday.

The nuclear accord, agreed under the presidency of Barack Obama, saw international sanctions eased in exchange for stringent controls on Iran's nuclear programme and closer IAEA inspections. 

Trump has signalled he is ready to abandon what he has labelled the "worst deal ever" as early as next month.

If the White House "decertifies" Iran's compliance, it would open the way to the US Congress re-imposing sanctions and perhaps provoke Iran to itself pull out

The other world powers - France, Britain, Germany, China and Russia - who signed the accord continue to see it as the best way to prevent Iran from building a bomb.

"France will try to persuade President Trump of the importance of this choice, even if it can be completed by work for after 2025", French Foreign Minister Jean-Yves Le Drian said on Monday ahead of a meeting between Trump and French President Emmanuel Macron.

Le Drian warned that scrapping the "essential" agreement would launch a regional arms race between "neighbouring countries."

Under the deal, limits on Iran's uranium enrichment will begin to expire in 2025 under "sunset clauses" and critics have said this is the weakest part of the deal.

"It's essential to maintain (the agreement) to prevent a spiral of proliferation that would encourage hardliners in Iran to pursue nuclear weapons," Le Drian said.

Hawks in Washington with support from Trump and some in his inner circle are calling for tougher sanctions on Iran's ballistic missile program, arguing that they would not breach their side of the nuclear-only deal.

Meanwhile, Trump's top foreign policy officials, UN Ambassador Nikki Haley and Secretary of State Rex Tillerson, have upped their rhetoric.

Haley went to Washington this month to deliver a speech laying out the case for Trump to find Iran in breach of the deal when he reports to Congress on October 15.

Despite US agitation at Iran's perceived breaching of the pact, Iran has said that it is willing to continue with the deal as long as its five other signatories remain committed.

A report released by the International Atomic Energy Agency bolstered the Iranian position when it confirmed that Tehran was keeping within the terms of the agreement.