UN Chief "deeply concerned" by US decision to exit Iran-nuclear-deal

"I have consistently reiterated that Joint Comprehensive Plan of Action (JCPOA) represents a major achievement in nuclear non-proliferation and diplomacy and has contributed to peace and security," Guterres said.

JCPOA reached by Iran, China, France, Germany, Russia, UK, US, and European Union sets out rigorous mechanisms for monitoring restrictions placed on Iran's nuclear program, paving the way for lifting UN sanctions against the country.

"It's essential that all concerns regarding the implementation of Plan be addressed through mechanisms established in JCPOA," Guterres said, adding that "issues not directly related to JCPOA" should be addressed separately, "without prejudice to preserving the agreement and its accomplishments."

The UN chief called on other JCPOA participants to abide by their respective commitments and on all other member states to support the agreement.

At the Board of Governors meeting in March, IAEA chief Yukiya Amano had said that Iran was abiding by the deal and IAEA inspectors had been given access to all sites and locations, upon request.

"If the Joint Comprehensive Plan of Action (JCPOA) were to fail, it would be a great loss for nuclear verification and for multilateralism," he said.

The leaders of France, Germany, and the UK have expressed regret and concern over Trump's decision to withdraw the US from JCPOA.

A joint statement from UK PM Theresa May, German Chancellor Angela Merkel, and French President Emmanuel Macron emphasized their "continuing commitment" to JCPOA.

They urged US to "avoid" taking action which "obstructs" its full implementation by all other parties to the deal.

"Iran must continue to meet its own obligations under the deal, cooperating fully and in a timely-manner with IAEA inspection requirements," the joint statement said.

"IAEA must be able to continue to carry out its long-term verification and monitoring-program without restriction or hindrance. Iran should continue to receive the sanctions relief it is entitled to whilst it remains in compliance with deal," it added.