DUBAI (Reuters) - Senior U.N. nuclear watchdog officials began talks in Iran on Wednesday to nail down an elusive deal for access to pursue a long-stalled investigation into suspected military dimensions to the Iranian nuclear programme.
The International Atomic Energy Agency, whose mission is to prevent the spread of nuclear weapons, has been trying for a year to negotiate a so-called structured approach with Tehran that would give it access to officials, documents and sites.
Iran's ISNA news agency reported the start of the talks at Iran's Atomic Energy Organisation headquarters in Tehran.
World powers will monitor the IAEA-Iran talks for any signs as to whether Tehran, facing intensifying sanctions pressure, may be prepared to finally start tackling mounting international concerns about its nuclear activity.
The six powers - the United States, France, Germany, China, Russia and Britain - and Iran may later in January resume their separate negotiations to try and reach a broader diplomatic settlement. They last met in June.
Israel - a U.S. ally believed to have the Middle East's only nuclear arsenal - has threatened military action if diplomacy and economic sanctions intended to rein in Iran's uranium enrichment programme do not resolve the stand-off.
The IAEA's immediate priority was to visit the Parchin military base southeast of Tehran, where it suspects explosives tests relevant for production of nuclear weapons may have taken place, perhaps a decade ago, accusations Tehran denies.
Western diplomats say Iran has worked for the past year to remove any incriminating evidence from Parchin, but IAEA chief Yukiya Amano said late last year a visit would still be useful.
Before leaving Vienna, IAEA Deputy Director General Herman Nackaerts said he was looking to finalise the agreement with Iran during the visit and that his team was ready to visit Parchin immediately if access were granted.
Tehran says a framework accord with the IAEA should be reached first before any visit to Parchin is granted.
Western diplomats voiced scepticism in the run-up to Wednesday's talks that a breakthrough was in the offing. Even if there were a deal, they say, it would be remained to be seen how it was implemented in practice.
A group of U.S. nonproliferation experts called in a report published this week for "maximal sanctions pressure" on Iran.
Three rounds of talks between Iran and the six world powers last year have "demonstrated that the United States and its allies do not yet have sufficient leverage to make Iran's leadership yield and agree to meet Iran's obligations under international law", they said.
(Reporting By Marcus George and Yeganeh Torbati in Dubia; additional reporting by Fredrik Dahl in Vienna; Editing by Mark Heinrich)