The UN nuclear agency chief has said that talks with Iran have been "going around in circles", with no progress on efforts to clarify concerns about its nuclear programme.
Yukiya Amano, director general of the International Atomic Energy Agency, said Iran's atomic work was in "clear contravention" of UN security council regulations.
In comments to the IAEA's 35-nation Board of Governors, he also said Iranian advances in building a heavy-water research reactor and in its uranium enrichment work were in "clear contravention" of UN Security Council resolutions, dating to 2006, calling for a suspension in such activities.
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The IAEA has been trying since early 2012 to engage with Tehran over what the Vienna-based UN agency calls the
"possible military dimensions" to Iran's nuclear programme.
But 10 rounds of negotiations in the last 17 months have failed to achieve any breakthrough. Western diplomats accuse
Iran of stonewalling the IAEA, an allegation Tehran rejects.
"Despite the intensified dialogue between the agency and Iran since January 2012..., no agreement has been reached on the structured approach document. To be frank, for some time now we have been going around in circles," said Amano.
Amano spoke at a time of apparent deadlock in a broader diplomatic initiative by six world powers to find a peaceful solution to the decade-old dispute over Iran's nuclear ambitions.
Western diplomats say they are awaiting the outcome of Iran's June 14 presidential election but do not anticipate any notable shift in the country's nuclear defiance.
Iran, under harsh Western sanctions, says its nuclear programme aims to meet the electricity needs of a rapidly growing population and advance some areas of scientific research.