UN Security Council resolutions. Iran must co-operate fully with the UN watchdog, the International Atomic Energy Agency (IAEA), Mr Medvedev said. China also said Iran should work with the UN watchdog, a foreign ministry spokesman said in Pittsburgh. Underground plant Speaking in New York, where he has been attending the UN General Assembly, Iran's President Ahmadinejad struck a defiant tone after the Pittsburgh proclamations. "It's not a secret site. If it was, why would we have informed the IAEA about it a year ahead of time?" he said. Please turn on JavaScript. Media requires JavaScript to play. He insisted Iran was acting within the boundaries of IAEA rules, saying it does not need to inform the agency of any new site until 180 days before any nuclear materialis placed within it. The existence of Iran's first enrichment plant, at Natanz, was only confirmed after intelligence emerged from Iranian exile groups several years ago. Western governments are said to have known of the existence of the new enrichment plant for some time. Mr Obama was first told about it during the "transition" period before he took office in January, officials say. In Washington, US officials said the Western nations decided to reveal their intelligence assessments when the Iranians realised the plant's secrecy was compromised. IRAN'S NUCLEAR SITES Iran insists that all its nuclear facilities are for energy, not military purposes Bushehr: Nuclear power plant Isfahan: Uranium conversion plant Natanz: Uranium enrichment plant, 4,592 working centrifuges, with 3,716 more installed Second enrichment plant: Existence revealed to IAEA