Before departing Tuesday for Iran, U.N. team leader Herman Nackaerts said the International Atomic Energy Agency hoped to "finalize the structured approach" that would outline what the agency can and cannot do in its investigation.
The U.N. nuclear watchdog agency wants to revisit Parchin, a military site southeast of Tehran, to probe allegations that Iran may have tested components needed to develop a nuclear weapon. Tehran has steadfastly denied any such activity.
Iran says agency's suspicions are based on forged intelligence provided by the CIA, the Israeli Mossad, Britain's MI-6 and other intelligence agencies, and that it has not been allowed to see the materials to respond to them.
Iranians say they have a bitter memory of allowing IAEA inspections and providing replies to a long list of queries over its nuclear program in the past decade. Now, Tehran says such queries should not be revived or remain open-ended once the IAEA has verified them.
Iran's Foreign Ministry spokesman Ramin Mehmanparast said Tuesday that Iran provided detailed explanations to IAEA questions on six outstanding issues in the past but instead of giving Iran a clean bill of health, the agency leveled new allegations on the basis of "alleged studies" provided by Iran's enemies.
Iran uses that term to refer to allegations about Parchin and other claims that it says the IAEA levels only to keep the issue alive.
Tehran has in the past allowed IAEA inspectors twice into Parchin, but now it says any new agency investigation must be governed by an agreement that lays out the scope of such a probe.
"Obligations of the other party must be clearly specified. If a claim is to be raised on a spot in Iran every day and (the U.N. agency) seeks to visit our military facilities under such a pretext ... this issue will be unending," Mehmanparast said Tuesday.
The talks come as Iran and six world powers prepare to meet, tentatively later this month. The six nations —the United States, Russia, China, Britain, France and Germany — hope the talks will result in an agreement by the Islamic Republic to stop enriching uranium to a higher level that could be turned relatively quickly into the fissile core of nuclear arms.
Iran denies such aspirations, insisting it is enriching only to make reactor fuel and to make isotopes for medical purposes.