Vienna: World powers and Iran on Sunday said big differences remained in talks to build a lasting agreement on the Islamic republic`s nuclear activities by the end of next week, as foreign ministers flew into Vienna to push negotiations along.
"We have some very significant gaps," US Secretary of State John Kerry told reporters on arrival.
"On practically all the important issues differences persist and we have not been able to narrow them," one of Iran`s top negotiators, Abbas Araqchi, told Al-Alam television.
The unbridged positions threaten to prevent the much sought-after, historic deal being struck by its July 20 deadline, when a six-month interim accord with Iran runs out.
If no agreement is reached by Sunday next week, both sides can decide to extend the interim pact for some weeks or months to keep talking.
In a sign of the high stakes at play, Kerry and the foreign ministers of France, Britain and Germany arrived in Vienna today to face off with Iranian counterpart Mohammad Javad Zarif.
Russia and China, the other two members of the P5+1 group comprising the five permanent UNSC members states plus Germany, were sending only lower-ranking officials, however.
Kerry, coming directly from Afghanistan where he brokered a breakthrough to end an election crisis there, will also seek to ease a major row over spying with Germany, which saw the CIA chief in Berlin expelled from the country.
Speaking about the Iran talks, Kerry said: "We need to see if we can make some progress," adding that "it is vital to make certain that Iran is not going to develop a nuclear weapon, that their programme is peaceful".
British Foreign Secretary William Hague echoed that, saying that the differences meant "it is unlikely that there will be a quick breakthrough today".
French Foreign Minister Laurent Fabius said that if a deal was not struck by next Sunday, "we either extend, a so-called rollover, or we will have to say that unfortunately there is no perspective for a deal".
He added: "We don`t know yet. It`s not yet July 20. We are trying to go in the right direction."
Araqchi, in his interview with Al-Alam, said "differences have been narrowed" on "certain" other issues and "some solutions have been put forward" in the final-round negotiations, which started on July 3.
But on the major divergences, "it is still not clear if we will get there," he said.