"The agency continues … to verify the non-diversion of declared nuclear material in Iran, but we cannot confirm that all nuclear material in Iran is in peaceful activities because Iran has not provided the agency with the necessary cooperation," Amano said in his opening address to the IAEA's board of governors.
Amano also said that a UN-brokered deal to supply Iran with much-needed fuel for a nuclear research reactor is "remains on the table".
"I believe it would ensure continued operation of the Tehran Research Reactor and serve as a confidence-building measure," he told the IAEA board of governors as they began a four-day meeting.
On Sunday, Iran's supreme leader Ayatollah Ali Khamenei accused the IAEA of lacking independence and being "influenced by the United States."
In a report 10 days ago, Amano expressed concern that Tehran may be "currently" working on a nuclear warhead. He also said Iran has started enriching uranium to higher levels — theoretically bringing it close to levels needed for weapons.