Diplomats familiar with the progress of Iran nuclear talks say some differences have been narrowed between Tehran and six world powers. But they report little progress on the main dispute, with Iran resisting U.S.-led attempts to place strict constraints on its uranium enrichment program, according to the Associated Press.

Enriched uranium can be used for reactor fuel or to arm nuclear weapons, depending on the level of enrichment. Iran says it does not want such arms and is pushing to keep its present enrichment capacity. Washington and its allies seek deep cuts in the nearly 20,000 centrifuges Iran has operating or on standby, and other restrictions.

The two diplomats spoke Friday, June 20, the last planned day of the current negotiating round. They demanded anonymity because they are not authorized to discuss the confidential talks.