Fresh talks between world powers and Iran over Tehran's nuclear programme have begun in Baghdad.

Negotiators from the US, UK, China, Russia, France and Germany sat down with a team of Iranian diplomats to try to hammer out specific goals in the long impasse.

Iran is demanding that the West outline timetables and steps ahead to gradually address international concerns over the Islamic Republic's nuclear ambitions.

Tehran hopes to leave the Iraqi capital with a clear framework for future talks and potential deal-making, an Iranian official said.

Western diplomats have voiced similar concerns, although few believe the discussions in Baghdad will yield breakthroughs in the showdowns over Iran's nuclear intentions.

The US and its allies fear Iran could use its nuclear expertise to build atomic weapons. Iran claims it only seeks nuclear reactors for energy and research.

Iranian negotiators would not identify specific offers or benchmarks they wanted to see by the day's end. The US has also been vague about its goals, with officials saying the talks will explore elements of a possible agreement.