VIENNA A senior U.S. official said some progress was made in high-level nuclear negotiations with Iran on Wednesday but much work remained to be done, adding the goal was still to reach a deal by a late November deadline.
The State Department official spoke after about six hours of talks between U.S. Secretary of State John Kerry, Iranian Foreign Minister Mohammad Javad Zarif and European Union foreign policy chief Catherine Ashton in Vienna.
Iran and six world powers - the United States, France, Germany, China, Russia and Britain - aim to end a decade-long nuclear standoff by a Nov. 24 target date, although Tehran and Moscow have both indicated that more time may be required.
With less than six weeks to go, Western officials say important differences still remain, especially over the future scope of Iran's production of enriched uranium, which can have civilian as well as military uses.
"We’ve been chipping away at some of the issues. Everybody has put ideas on the table to see if we can move the ball forward," said the U.S. official, who declined to be named.
"We have and continue to make some progress but there's a substantial amount of work to be done," the official said.
The negotiations are centered on curbing Iran's atomic activity, which Tehran says is peaceful but the West fears may be aimed at developing nuclear weapons capability, in exchange for lifting sanctions.
"We hope Iran decides to take advantage of this historic opportunity," the senior U.S. official said.
"We can foresee a way forward through a verifiable agreement that both resolves the international community’s concerns about ... Iran’s nuclear program and also provides the Iranian people with more economic opportunity and an end to isolation," the official added.
Senior officials from the six powers and Iran are due to meet on Thursday in the Austrian capital.
There was no immediate indication that Kerry would stay on for further talks on Thursday, which would mean deviating from his plan to head back to Washington early in the morning.
RUSSIA SAYS DEADLINE DATE 'NOT SACRED'
Iran's Parliament Speaker Ali Larijani said in Geneva the United States should stop focusing on the number of Iran's uranium enrichment centrifuges, which he described as a "trivial matter," and concentrate on pushing for a deal.
Western governments want Iran to cut its centrifuge capacity to the low thousands so that it would take Tehran a long time to purify enough uranium for an atomic weapon. Tehran has rejected demands to significantly reduce the number below the 19,000 it has now installed, of which roughly half are operating.
The U.S. official said gaps in negotiating positions would have to be narrowed in a way that "ensures that all of the pathways for fissile material for a nuclear weapon are shut down."
Regarding Iran's Arak reactor, which the West fears could yield plutonium for bombs, the official said "we have some possible solutions to that".
One of Iran's chief negotiators, Deputy Foreign Minister Abbas Araqchi, last week raised the possibility the talks could be extended, and Russian Foreign Minister Sergei Lavrov said on Tuesday that the deadline was not "sacred".
Asked whether an extension has been discussed or has been ruled out or not, the senior U.S. official said: "We have not discussed an extension. We believe in keeping the pressure on ourselves... you never say never, but today we are focused on Nov. 24 and Nov. 24 only.”
Lavrov, speaking on Tuesday in Paris, where he met Kerry, said he was "sure that a compromise is possible" in the negotiations with Iran.
"I can’t guarantee you that it would be reached by November 24. This date is not sacred," he told Russian television.
Iran rejects Western allegations that it is seeking nuclear weapons capability, but has refused to halt uranium enrichment, and has been hit with U.S., EU and U.N. Security Council sanctions as a result. Israel has threatened possible military action against Iran if it is not satisfied with any deal.
(Additional reporting by Fredrik Dahl in Vienna, Vladimir Soldatkin in Moscow and Tom Miles in Geneva; writing by Fredrik Dahl; editing by Dominic Evans, Angus MacSwan and Gunna Dickson)