Iran had put off inspections scheduled for last week in order to protest a tough resolution by the watchdog International Atomic Energy Agencyagainst Tehran for hiding sensitive parts of a weapons program that the United States claims is devoted to secretly developing nuclear arms.
"I hope and trust there will be no further delays in respect to any future inspection in Iran. It is clearly in the interest of Iran to cooperate fully with the IAEA," the agency's chief Mohamed ElBaradei told reporters on a visit to Washington, where he is to meet Wednesday with US President George W. Bush.
ElBaradei said Iranian authorities had told him "the new date for inspectors' arrival in Iran would be on the 27th of March."
He said this would be in time for the IAEA to report its findings on Iran to the next IAEA board meeting in Vienna in June.
Non-proliferation analyst Jon Wolfsthal said "the Iranians are playing a double game" since they have to appease a nationalistic domestic audience.
"They stand on principle and ask for a halt to inspectioins for a weekend and then on Monday say OK we stood by our guns and are now prepared to let you guys back in," said Wolfsthal from Washington's Carnegie Endowment for International Peace.
He said the IAEA would like to see Iran follow the Libyan model, of pro-actively giving information on its nuclear program.
This was especially true since Libya and Iran both got supplies from the same Pakistani-run black market.
The IAEA is looking for "weapons designs and uranium hexafluoride gas" in Iran that is used to enrich uranium, Wolfstahl said, adding that "if Libya got them (from the smuggling network) and we think North Korea got them, then everybody thinks Iran got them too."
ElBaradei, who met Monday with non-proliferation advocate Republican Senator Richard Lugar, said the Iranian halt "was clearly always regarded as a temporary expression of the dissatisfaction with the resolution adopted last week" at the IAEA board meeting in Vienna.
"I'm glad they have reversed that decision in a very short period of time," he said.
Experts have said Iran could be developing the technology to make atomic weapons, even while honoring the nuclear Non-Proliferation Treaty (NPT) by claiming its nuclear program is peaceful. Much of sensitive nuclear technology, such as enriching uranium, can have both civilian and military applications.
The IAEA said in a report issued last month that Iran had failed to report possible weapons-related atomic activities despite promising full disclosure.
Iran had not told the IAEA it had designs for sophisticated "P-2" centrifuges for enriching uranium that could be weapon-grade, the report said.
ElBaradei said the IAEA's discovery in January of P-2 designs was "a setback, a great setback" since Iran had claimed in October to have fully disclosed its nuclear activities.
ElBaradei said the inspections starting March 27 were "to clarify some of issues around the P2 and going to the pilot plant (for making enriched uranium) at Natanz (in southern Iran) to make sure it is locked. it is sealed, it is not operational."
Iran had pledged in October to suspend the enrichment of uranium as a confidence-building measure with the IAEA.
A major remaining issue is whether traces of highly enriched uranium, that could be weapon-grade, found by the IAEA at two sites in Iran were homemade or came from contamination from centrifuge parts bought on a black market abroad, as Iran claims.
"We need all the support from Iran (to resolve this) but also need support from the importing country," ElBaradei said, referring to environmental samples the IAEA wants to take in Pakistan on centrifuge parts there.