Iran and world powers said today that their nuclear talks were now moving up a gear, with Tehran's foreign minister saying both sides agreed on "50-60 per cent" of issues.
Speaking after the latest round of talks in Vienna, the powers' chief negotiator, EU foreign policy chief Catherine Ashton said the next round from May 13 would see negotiations "move to the next phase".
A senior US official said that the next meeting, also in Vienna, would see Iran and the five permanent members of the UN Security Council plus Germany "begin actually drafting the text".
But in a statement repeated by Iran's Foreign Minister Mohammad Javad Zarif, Ashton said a "lot of intensive work will be required to overcome the differences which naturally still exist".
"I can say we agree on 50-60 per cent of issues, but the remainders are important ones and diverse," Zarif told Iranian media. "Even two per cent can torpedo all of it".
And in a sign of the difficulties ahead, the US official said that one issue remained Iran's ballistic missile programme, which Tehran has said is not up for discussion within the nuclear talks.
Zarif said also that Iran's negotiators have "put forward our stance that none of our (nuclear) facilities would be dismantled", one of the West's probable main demands.
"I would caution everyone from thinking a final agreement is imminent or that it will be easy. As we draft, I have no doubt this will be quite difficult at times," the US official said.
China's envoy Wang Qun said the latest round had been "fruitful" and that the talks were "building momentum".
In November the two sides reached an interim deal under which Iran froze certain parts of its nuclear activities in return for minor relief from painful Western sanctions.
But Iran has not permanently dismantled any of its nuclear equipment and can fully reactivate its facilities if it wishes when the deal expires on July 20, the deadline for agreeing a final deal.
US Secretary of State John Kerry told US lawmakers Monday that the theoretical period needed for Iran to produce a weapon's worth of bomb material -- if it chose to do so -- was "about two months".
