The head of the UN atomic agency will visit Iran Monday, the IAEA said in a surprise announcement that raised hopes of a deal on closer cooperation just days ahead of major talks with world powers.
Yukiya Amano will leave Vienna on Sunday for talks on Monday with senior Iranian officials including chief nuclear negotiator Saeed Jalili, the IAEA said.
The trip comes ahead of a Wednesday meeting in Baghdad between Iran and the P5+1 powers: the United States, Russia, China, France, Britain and Germany -- plus the European Union -- that are aimed at laying the groundwork to resolving the long-running crisis over Iran's nuclear programme.
Amano, accompanied by IAEA chief inspector Hermann Nackaerts and agency number two Rafael Grossi, would meet other "senior representatives of the Iranian government" for talks "to discuss issues of mutual interest," in his first trip to Iran since becoming head of the IAEA, the agency said.
They are likely to press Iran to address a major IAEA report in November alleging that until 2003, and possibly since, Tehran had a "structured programme" of "activities relevant to the development of a nuclear explosive device."
That report has contributed to tensions this year, with the United States and European Union imposing further sanctions targetting Iran's vital oil sector, and raising speculation that Israel may bomb its arch rival's nuclear sites.
Diplomats speaking to AFP on condition of anonymity said the fact that the Japanese Amano himself was going raised hopes of a breakthrough, with one Western envoy saying Tehran "had its back against the wall."
Another Vienna diplomat told AFP that the surprise announcement was a "hopeful" sign, while a third said they expected Amano to "conclude the negotiations on the modalities (of cooperation) and to have it formalised in a document.
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"But you shouldn't count your chickens until they are hatched. We will need to wait until Monday. Iran is a very special customer," the diplomat cautioned.
In two visits to Iran in January and February by Nackaerts, the IAEA said Iran continued to reject out of hand the claims made in the November report as founded on lies provided by its enemies.
The document was based on information from around 10 foreign intelligence agencies, the IAEA's data such as satellite imagery and information from Iran itself. The agency called its sources broadly "credible."
The IAEA also said that Iran denied Nackaerts in his visits access to the Parchin military base where the agency believes suspicious explosives testing took place in a large metal container.
Western countries have accused Iran of removing evidence at the site near Tehran and Amano has said satellite imagery showed unspecified activity. Iran has rejected any accusations of a clean-up.
The Iran trip replaces talks that had been set to resume on Monday in Vienna between Nackaerts and Iran's ambassador to the IAEA, Ali Asghar Soltanieh, the agency said.
Speaking to AFP, Soltanieh gave no further details, saying only that this "is a visit for talking about issues of common interest, and of course about cooperation with the IAEA."
Iran says its nuclear activities are peaceful but the International Atomic Energy Agency says it is unable to confirm this, and the UN Security Council has imposed four rounds of sanctions on Iran.
Closer Iranian cooperation with the IAEA is one of the areas where the P5+1 wants to see some movement, as well as on Iran's enrichment of uranium to 20-percent purities, in technical terms not far short of weapons grade of 90 percent.