Experts for Iran and 6 world powers work on Iran nuclear deal with 6 weeks to June deadline

Experts from Iran and six world powers are gathering in Vienna for the next round of negotiations meant to result in a nuclear deal curbing Tehran's atomic activities in exchange for sanctions relief.

The technical experts meeting Tuesday are to be joined by senior political officials from Iran, the United States, Russia, China, Britain, France and Germany later in the week. The sides are aiming for a comprehensive agreement by the end of June.

Diplomats say that some progress has been made in drafting an agreement but significant blank sections remain. The negotiators also are working on technical annexes outlining ways of implementing a deal and timeframes.

The six want limits on Iranian programs that could be used to make nuclear arms. Tehran denies any interest in such weapons.