Iran accused the United States on Thursday of pressuring the UN's nuclear agency to base its latest investigation of Teheran's nuclear activities on fake evidence suggesting Iran had a secret weapons program. It also threatened to sue countries that pushed to have UN Security Council involvement in its nuclear program, a clear allusion to the United States and its key allies. In pressuring Teheran on the nuclear issue, the US, France, Australia, Canada and Japan "wished to find an excuse for ... their hidden agenda, from the extreme of regime change to [the] deprivation of [the] Iranian noble nation from science and technology," said Ali Ashgar Soltanieh, Iran's chief delegate to the International Atomic Energy Agency. Speaking at the closing session of the 35-nation IAEA board, Soltanieh suggested the failed attempt to push Iran into concessions on its nuclear program and giving up uranium enrichment was only one example of a series of bad foreign policy decisions by Washington. "The US Administration has continuously miscalculated in dealing with world affairs," he said in comments to the closed meeting made available to media. "The dark record in our region clearly proves this assertion." Since beginning its investigation last year into allegations of a secret Iranian nuclear weapons program, the IAEA has asked in vain for substantive explanations for what seem to be draft plans to refit missiles with nuclear warheads; explosives tests that could be used for a nuclear detonation; military and civilian nuclear links; and a drawing showing how to mold uranium metal into the shape of warheads. Iran remains defiant, saying the evidence from the US and other board members purportedly backing the allegations was fabricated. Soltanieh expanded on those charges Thursday, challenging IAEA statements that the investigation was based on intelligence and other information from 10 board member nations. "Except for one document, all documents ... have been provided to the agency by the US," he said, adding that briefings on the alleged weapons activities were based on "fabricated" evidence "because of the pressures imposed by the US." Iran is also under fire for defying three sets of UN Security Council sanctions and continuing to enrich uranium - which can generate both nuclear fuel and the fissile material for the core of nuclear warheads. In a warning to the US and other nations that pushed for Security Council involvement in Iran's nuclear file, Soltanieh said Teheran had "the right to resort to legal actions to seek redress against the sponsors of these unlawful actions."