Western diplomats said last week Iran had expressed readiness to restart discussions with the International Atomic Energy Agency (IAEA) two months after their last meeting ended in failure.
But they added that Tehran still appeared to be stonewalling over the body's most pressing demand to let its inspectors visit a key military site.
Iran's ambassador Ali Asghar Soltanieh told the IRNA news agency Tehran's decision "shows the peaceful nature of all of its nuclear activities, while showing that claims against Iran are baseless."
Washington and its allies believe Tehran is working on developing nuclear bombs. Tehran insists its activities have only civilian aims.
The IAEA last year issued a report detailing alleged Iranian research and development activities that were relevant to nuclear weapons, lending independent weight to Western suspicions.
Iran has refused to stop enriching uranium, despite a slew of sanctions. Iran has also restarted negotiations with six world powers over its nuclear programme and the sides have agreed to meet again in Baghdad on May 23.
Iranian Foreign Minister Ali Akbar Salehi said on Monday Iran was optimistic that the talks with US, Russia, China, Germany, France and Britain would make progress.
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