IAEA Director General Yukiya Amano told the Board of Governors on Monday in Vienna that Iran has installed updated centrifuges at its nuclear enrichment plant in Natanz. Inspectors haven't been able to visit the Parchin military complex outside Tehran to better understanding of what type of activity is under way there.
"Providing access to the Parchin site would be a positive step, which would help to demonstrate Iran's willingness to engage with the agency on the substance of our concerns," Amano said.
Alaeddin Boroujerdi, chairman of Iran's national security committee, said in January there was no nuclear work under way at Parchin.
Iran is suspected of pursuing the technology needed to manufacture a nuclear weapon, an allegation Tehran denies. The government described last month's multilateral nuclear negotiations in Kazakhstan as positive, though no major breakthroughs were announced.
Amano said the Iranian government, however, wasn't cooperating with inspectors regarding their nuclear intentions.
"The agency therefore cannot conclude that all nuclear material in Iran is in peaceful activities," he said.