Iran's threat to withdraw from a global non-proliferation treaty if European countries refer it to the UN for violations of the 2015 nuclear deal would send "a very, very negative message", a US ambassador said on Tuesday.

Iran's Foreign Minister Mohammad Javad Zarif on Monday was quoted by Iranian news agencies as saying: "If the Europeans continue their improper behaviour or send Iran's file to the Security Council, we will withdraw" from the Nuclear Non-Proliferation Treaty (NPT).

Following Zarif's comments, US disarmament envoy Robert Wood denounced Iran for "threatening to walk away from" the Cold War-era pact.

"We think that Iran needs to end its malign behaviour and sit down with the United States and negotiate an agreement that deals not only with the nuclear issue but also with the other issues that concern us like the ballistic missile proliferation," the US envoy said.

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Since its foundation in 1968, the NPT has regulated global nuclear weapons proliferation by banning its 190 members - other than the US, Russia, China, Britain, and France - from acquiring atomic arms. However, the treaty allows signatories to develop peaceful nuclear technology overseen by the UN.

Iran, which joined the NPT in 1970, agreed to constrain its nuclear activity in exchange for sanctions relief by signing the 2015 nuclear deal.

Tehran gradually scaled back its obligations under the accord following President Donald Trump's decision to pull the US out of the agreement in 2018 and reimpose crushing American sanctions that have severely harmed the Iranian economy.

'Different options'

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Three European signatories triggered a dispute resolution mechanism last week over Iran's breaches of the accord, which could see the matter referred back to the Security Council and the reimposition of UN sanctions.

Iran contends its violations are justified by the Europeans' failure to uphold their end of the bargain in securing its economic benefits guaranteed under the accord.

"If the Europeans return to the commitments, Iran will also stop reducing its commitments, but if the Europeans continue as they have been ... we have different options," said Zarif on Monday.

Iran's ambassador to the United Nations in Geneva, Esmaeil Baghaei Hamaneh, told a UN-backed disarmament conference on Tuesday that Tehran is willing to get the accord back on track.

"Iran has said steps taken in full conformity with JCPOA [nuclear deal] will be reversible should other JCPOA participants take meaningful decisions to live up to their commitment," Hamaneh said.

Reports issued by the UN nuclear watchdog have suggested Tehran is still far from sprinting ahead with uranium enrichment.