MOSCOW: Expert talks between world power and Iran over Tehran's nuclear programme produced no breakthrough but were positive in tone, Russia's chief negotiator on the dispute said on Thursday.

"There was certain progress. It was real but insufficient to speak of a breakthrough," Deputy Foreign Minister Sergei Ryabkov told reporters after the talks in Istanbul on Monday.

Ryabkov said the two sides "still had a lot of homework to do" before a fifth round of higher-level political discussions in Almaty on April 5-6.

The European Union said on Tuesday that the world powers -- the five permanent UN Security Council members and Germany -- gave Iran fresh details on a proposed deal aimed at ending international concern over Tehran's nuclear drive.

The six states last month offered Iran an easing of non-oil or financial sector-related sanctions in exchange for concessions over Tehran's sensitive uranium enrichment operations.

The offer in return demands a tougher nuclear inspection regime and the interruption of enrichment operations at the Fordo bunker facility where 20-percent enrichment goes on.

The West suspects Tehran is seeking to develop nuclear weapons under the guise of what the Islamic republic insists is a purely civilian programme with peaceful ends.