Yukiya Amano and Rex Tillerson
© AFPU.S. Secretary of State Rex Tillerson (right) and International Atomic Energy Agency Director Yukiya Amano.
The head of the United Nations' atomic watchdog says he is confident after a visit to Washington that there will be "very good cooperation" with the United States on Iran's nuclear deal, despite harsh criticism of the agreement by U.S. President Donald Trump.

International Atomic Energy Agency (IAEA) Director-General Yukiya Amano made the remarks in Vienna on March 6 following a visit to Washington where he met with U.S. Secretary of State Rex Tillerson.

Neither the IAEA nor the U.S. State Department has commented on the content of Amano's March 2 meeting with Tillerson.

The 2015 agreement between Iran and six world powers restricts Tehran's nuclear activities in exchange for the lifting of international sanctions against Iran.

But Trump has called the accord "the worst deal ever negotiated" and said he wants to "police that contract so tough [that the Iranians] don't have a chance."

Amano's remarks on March 6 were the first indication of how his talks in Washington had gone.

But Amano did not provide specific details about what Tillerson told him.