Iranian workers stand in front of the Bushehr nuclear power plant, about 1,200 km south of Tehran October 26, 2010. (Image: Reuters)
The technical talks in Vienna with the International Atomic Energy Agency (IAEA) come in addition to negotiations with the six world powers - U.S., Britain, France, Russia, China and Germany - set for May 23 in Baghdad.
Iran and the IAEA have been at loggerheads over the agency's inspections of Iranian military sites. IAEA inspectors have demanded access to a military complex where the agency suspects secret atomic work has been carried out. Iran says inspectors will be allowed to visit the Parchin military site as a goodwill gesture, but it would require agreement between the two sides on guidelines for the inspection.
IAEA officials have said satellite photos of Parchin show an apparent clean-up under way, adding they fear protracted talks on a framework for the visit could be a delaying tactic.
Iran has rejected such allegations as misleading, saying any alleged radioactive traces could not be cleaned up.
The U.S. and some of its allies accuse Iran of using its civilian nuclear programme as a cover to develop nuclear weapons. Iran has denied the charges, saying its nuclear programme is peaceful and aimed at producing electricity and radioisotopes to treat cancer patients.