Vienna: Officials from Iran and Britain, France and Germany were due on Thursday to hold nuclear talks in Vienna towards reaching a potentially historic accord by November.
The three European countries form part of a six-nation group including the United States, Russia and China due to resume negotiations with Iran in New York on September 18.
The closed-door discussions in the Austrian capital, announced by EU foreign policy chief Catherine Ashton`s office, follow bilateral US-Iranian discussions in Geneva last week.
A US State Department spokeswoman told reporters on Tuesday that those talks in Switzerland were an "in-depth exchange on the core issues", without giving further details.
The recent diplomatic flurry also saw Iranian Foreign Minister Mohammad Javad Zarif fly to Moscow, Brussels and Paris as well as Rome to meet Ashton`s successor from November 1, Federica Mogherini.
The P5+1 powers, all of which except Germany sit on the UN Security Council and have nuclear weapons themselves, want Iran to scale back its atomic programme to ease fears the Islamic republic gets the bomb.
Tehran, which says its nuclear programme is exclusively for electricity generation and medical uses, in return wants painful UN and Western sanctions lifted.
On July 18, two days before a deadline to get a deal and after months of intense talks, negotiators from Iran and the six powers decided to give themselves until November 24 to nail down the accord.