The chief of the UN atomic watchdog has said he is confident of “very good cooperation” with the US on Iran’s nuclear deal, despite Donald Trump’s hawkish comments.

The 2015 agreement between Iran and major powers restricts Tehran’s nuclear activities in exchange for the lifting of sanctions against the Islamic Republic, but Trump has called it “the worst deal ever negotiated” and said he wants to “police that contract so tough [the Iranians] don’t have a chance”.

“I am confident that we can have very good cooperation with the United States in the future,” Yukiya Amano, chief of the International Atomic Energy Agency (IAEA), told a news conference in Vienna following a visit to Washington.

Amano met the US secretary of state, Rex Tillerson, in Washington last Thursday. During his confirmation hearing Tillerson had called for a “full review” of the deal, which extends the time Iran would need to produce a nuclear weapon if it chose to.

Since Trump took office in January, however, his administration has given little indication of what concrete stance it will take on the Iran agreement.

Neither the IAEA nor the US state department commented on the content of last week’s meetings, which were Amano’s first with senior members of the Trump administration.

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Amano’s remarks on Monday, the first day of a quarterly meeting of the IAEA board of governors, were the first indication of how the talks in Washington had gone, though he did not provide specific details on what Tillerson told him.

“With respect to Iran I made the point that the JCPOA is a net gain from the verification point of view because now we have the strongest verification regime in Iran, while the nuclear activities of Iran are reduced,” Amano said, calling the deal by its full name, the Joint Comprehensive Plan of Action.

“The new administration of the United States just started and they are looking at various issues – not just this issue but many other issues, so it is very early for them to give their assessment,” he added.

The IAEA is in charge of policing the restrictions on Iran’s nuclear activities under the deal agreed between Iran, the United States, Russia, China, Britain, France and Germany.

Amano also said on Monday he had not discussed with Tillerson his bid for a third term as head of the IAEA, which is on the agenda of this week’s board meeting.

The US is one of the few countries not to have publicly backed Amano, who is the only candidate.