Iran and six world powers will hold a new round of nuclear talks before the UN General Assembly, which starts on September 16, a spokesman for lead negotiator Catherine Ashton said Thursday.

"We expect to hold an EU-led/E3+3 round of talks in advance of the ministerial meetings at UNGA at a location to be determined," said Michael Mann, spokesman for EU foreign policy chief Ashton.

"We will also likely hold a meeting on the sidelines of UNGA -- as we did last year -- possibly with ministers participating in some way," Mann said in an emailed statement. "The specific details remain to be worked out."

Last month after several months of talks Iran and the five permanent members of the UN Security Council plus Germany decided to extend their self-imposed deadline of July 20 to strike an agreement until November 24.

Such an accord is aimed at easing fears once and for all that the Islamic republic might use its civilian nuclear programme to build an atomic bomb, something Tehran has always denied.

On Thursday US and Iranian officials were due to meet in Geneva for one-on-one talks, the State Department said.