UN spokesman Farhan Haq recalled that Guterres has consistently praised the Joint Comprehensive Plan of Action (JCPOA), as the deal is formally known, as a "major achievement in nuclear non-proliferation and diplomacy and has contributed to regional and international peace and security."

"He strongly hopes that the Joint Comprehensive Plan of Action can be preserved," he added.

President Hassan Rouhani told a cabinet meeting in Tehran that Iran would no longer abide by some limits imposed on its nuclear activities that were agreed under the deal with world powers.

Iran's Supreme National Security Council said it no longer considered itself bound by the agreed restrictions on stocks of enriched uranium and heavy water.

It said after 60 days, it would also stop abiding by restrictions on the level to which Iran can enrich uranium and modifications to its Arak heavy water reactor that were designed to prevent the production of plutonium.

US Secretary of State Mike Pompeo said the announcement was "intentionally ambiguous" and that Washington would wait and see what action Iran will take before deciding on a response.