The UN nuclear watchdog has been unable to inspect Iranian facilities affected by the war last June, according to a confidential report.
The International Atomic Energy Agency (IAEA) reported that it cannot provide information on Iran's enriched uranium stockpile or whether the country has suspended all enrichment-related activities.
The IAEA warned that it is unable to discharge its safeguards responsibilities under the Nuclear Non-Proliferation Treaty and urged Tehran to implement its obligations.
The only nuclear facility inspected in Iran since February has been the Bushehr nuclear power plant, which uses uranium from Russia enriched to 4.5 per cent.
Iran maintains a stockpile of 440.9 kg of uranium enriched up to 60 per cent purity, a short step away from weapons-grade levels.
IAEA director general Rafael Grossi warned that this stockpile could allow Iran to build as many as 10 nuclear bombs, should it decide to weaponise its programme.
