Israeli Prime Minister Benjamin Netanyahu made the claim in front of the UN General Assembly last week.

Without explicitly referring to Netanyahu's claim, IAEA chief Yukiya Amano insisted that the agency's independence was "of paramount importance" for its work.

The IAEA "uses all safeguards-relevant information available to it but it does not take any information at face value," Amano said in a statement.

Netanyahu accused Iran of operating a "secret atomic warehouse for storing massive amounts of equipment and material from Iran's secret nuclear weapons programme."

He urged the IAEA to inspect the site.

Amano said the IAEA would not be told how to do its work.

"All information obtained, including from third parties, is subject to rigorous review," he said.

He said the IAEA's work "must always be impartial, factual, and professional."

Under the 2015 deal, Iran agreed to scale down its nuclear activities and submit to IAEA inspections in exchange for relief from sanctions.

Israel bitterly opposes the deal and congratulated US President Donald Trump for walking away from it earlier this year.

The IAEA has repeatedly said that Iran is continuing to meet its commitments under the deal.

Amano said on Tuesday that evaluations of Iran's compliance were "ongoing".