The opening round of nuclear talks between Iran and six world powers has ended on a positive note, with both sides saying they had agreed on a plan for further negotiations meant to produce a comprehensive deal to set limits on Tehran's nuclear ambitions.
In a joint statement on Thursday, they said the next round of negotiations would begin in Vienna on March 17, continuing a process likely to take at least six months, probably longer.
The positive tone on a framework for future talks appeared to be aimed in part at proving to sceptics inside and outside Iran that the negotiations had a chance to succeed despite huge gaps between the Iranians and the six powers.
Iranian Foreign Minister Mohammad Javad Zarif, who came to the talks vowing Iran would never strip down its nuclear facilities, seemed relaxed as he read out the joint statement. But he told state TV afterwards that his nation would "not close down any site."
The six powers, the United States, Russia, China, Britain, France and Germany, want Tehran to agree to significant cuts in its nuclear programme to reduce concerns it could be turned to weapons use. Iran opposes cuts, saying its programme is not aimed at building weapons.
"We have...identified all of the issues we need to address for a comprehensive and final agreement," said Catherine Ashton, the EU's top diplomat who convened the talks.
"It won't be easy, but we've gotten off to a good start," she said in a statement read later in Farsi by Zarif.
A Western diplomat said Ashton would visit Tehran March 9-10 for preparatory talks.
From Baghdad, Russian Foreign Minister Sergey Lavrov said Moscow had the impression that "all sides are interested in being serious and being pragmatic."
The talks are designed to build on a first-step deal in effect since last month that commits Iran to initial nuclear curbs in return for some easing of sanctions. The deal can be extended by mutual consent after six months.
The six powers say Iran should dismantle or store most of its 20,000 uranium-enriching centrifuges, including some not yet working. They also want a reactor now being built to either be scrapped or converted from a heavy-water setup to a light-water facility that makes less plutonium.
Meanwhile, a unilateral US oil embargo on Iran is expected to remain in place even if a long-term nuclear agreement is reached, Reuters news agency reported.
The embargo pre-dates the decade-long nuclear dispute with Iran.
"The American domestic oil embargo is expected to remain in place even if a comprehensive agreement is reached," a US official told Reuters on condition of anonymity.