By Fredrik Dahl
VIENNA (Reuters) - The U.N. nuclear agency is expected to make a new attempt soon to advance its investigation into suspected atomic bomb research by Iran, diplomats said on Thursday, more than a month after Tehran missed a deadline for cooperation.
They said experts of the International Atomic Energy Agency and Iran may meet early next week in Tehran, with the IAEA seeking to achieve progress in the slow-moving inquiry into the country's nuclear program.
There was no immediate comment from the IAEA, a Vienna-based U.N. agency which for years has been trying to investigate Western allegations that Iran has worked on designing a nuclear warhead. Iran says its nuclear program is entirely peaceful.
Western officials say Iran must step up cooperation with the IAEA if it wants to reach a broader diplomatic deal with world powers that would end a decade-old nuclear dispute and gradually end crippling financial and other sanctions on the oil producer.
Early last month, the IAEA said Iran had failed to answer questions by an agreed Aug. 25 deadline about two areas of the investigation into alleged research activities that could be applicable to any attempt to make nuclear bombs - explosives testing and neutron calculations.
While rejecting the accusations as baseless, Iran has promised since Hassan Rouhani, seen as a pragmatist, became president last year on a platform to end its international isolation, to work with the IAEA to clear up the suspicions.
Rouhani's election raised hopes of a solution to the stand-off with the West after years of rising tension and fears of a new Middle East war. An interim accord was reached between Iran and six major powers - the United States, France, Germany, Britain, China and Russia - in Geneva last November.
But they did not meet a self-imposed July target date for a long-term accord and now face a new deadline of Nov. 24. Both sides said little headway was made in overcoming significant disagreements at the most recent round of talks that ended on Friday in New York.
While the powers seek to limit the size of Iran's future nuclear program - and thereby extend the time it would need for any bid to amass fissile material for a weapon - the IAEA is investigating alleged research and experiments in the past that could be used to make the bomb itself.
Western officials say that although there is no chance of the IAEA inquiry being completed before the scheduled end of the six-power talks, some of the sanctions relief Iran is seeking would probably depend on its cooperation with the U.N. agency.
The IAEA published a report in 2011 with intelligence indicating Iran had a nuclear weapons research program that was halted in 2003 when it came under increased international pressure, given the U.S.-led invasion of neighboring Iraq that same year and the exposure in 2002 by Iranian exiles of its underground enrichment plant at Natanz.
The intelligence suggested some activities may have resumed later. The report identified about 12 specific areas that it said needed clarification.
(Editing by Mark Heinrich)