"The agency is firmly committed to intensifying dialogue. We will continue negotiations with Iran on a structured approach to resolving all outstanding issues," Yukiya Amano told the Vienna-based agency's annual general conference.

"I hope we can reach agreement without further delay," he said.

Iran says its nuclear program is peaceful in purpose, but Western countries and Israel fear Tehran is developing an atomic bomb.

The latest round of talks between Iran and six world powers (the United States, Britain, China, Russia, France and Germany) in Moscow this summer yielded no breakthrough on what Iran says is its "non-negotiable" right to enrich uranium.

"Iran is not providing the necessary cooperation to enable us to provide credible assurance about the absence of undeclared nuclear material and activities," Amano said. "Therefore, we cannot conclude that all nuclear material in Iran is in peaceful activities."