World powers said Thursday that mooted talks with Iran must be "serious" and urged Tehran to allow UN inspectors access to a military base thought to be central to its suspected nuclear weapons drive.
"We call on Iran to enter, without preconditions, into a sustained process of serious dialogue, which will produce concrete results," said a statement from the United States, China, Russia, France, Britain and Germany, known as the P5+1.
They added that their readiness to negotiate was "on the understanding that these talks will address the international community's long-standing concerns and that there will be serious discussions on concrete confidence building measures."
The statement at a closed-door regular board meeting of the International Atomic Energy Agency, came two days after EU foreign policy chief Catherine Ashton said on behalf of the P5+1 that they were ready for talks with Iran.
Ashton said she did not want to "repeat the experience of Istanbul", referring to the last talks 14 months ago in the Turkish city, which broke down over Iranian demands to discuss "preconditions", according to Western envoys.
No date or location have been agreed but Washington's envoy Robert Wood to the IAEA told reporters Thursday he expected the talks to happen "in the coming few months."
Iran's envoy to the IAEA, Ali Asghar Soltanieh, declined to be drawn meanwhile on what concessions Iran might be prepared to make in the upcoming talks.
Tehran's willingness to discuss with the IAEA allegations of a nuclear weapons programme "by itself is confidence building," he told reporters.
"We will never suspend our nuclear activities, and we will continue (with them), under the supervision of course of the IAEA," he said.
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The possible resumption comes despite an apparent deadlock between the IAEA and Iran after two fruitless visits to Tehran led by chief inspector Herman Nackaerts in January and February.
The visits saw Iran again reject a major IAEA report in November outlining a host of suspicious nuclear activities and deny access to the Parchin military site where explosives testing for warhead research allegedly took place.
Thursday's P5+1 statement urged Iran to "fulfil its undertaking to grant access to Parchin."
Amano on Monday appeared to allege that Iran was removing evidence at the base, saying "activities" spotted by satellite "makes us believe that going there sooner is better than later."
Iran says the IAEA already visited Parchin near Tehran in 2005 and that it is under no obligation to allow access because the site is non-nuclear.
Nackaerts said that since 2005 "we have acquired new information -- from satellite imagery -- from which we have been able to identify the precise location where we believe an explosive chamber is situated."
Iran is highly sensitive about allowing access to military sites following a large explosion at the Bid Ganeh base in November and multiple assassinations of nuclear scientists it has blamed on Israel and the United States.
"The agency heard a lot of excuses from Iran," Wood, the US envoy, said Thursday. "When you have these reports about a possible clean-up going on, and the fact that the agency has been denied access, makes you wonder."
Soltanieh said allegations of "sanitization" of the site were "a childish (and) ridiculous story made out of nothing," describing Parchin as "one minor issue" in its negotiations with the IAEA, which he said were ongoing.
"Unfortunately Western countries are not telling the truth ... The truth is that Iran is not pursuing nuclear weapons," with sanctions having "no effect whatsoever" on Iran's nuclear activities, including enrichment, he said.