Iran's Foreign Minister Mohammad Javad Zarif will talk today with EU foreign policy chief Catherine Ashton over "serious differences" on how to implement a landmark nuclear deal, media reports said.
Technical talks began on Thursday between experts from Iran and the so-called P5+1 group of world powers over the nuclear accord clinched last month and stretched into a fourth day in Geneva.
Zarif said he was scheduled to speak to Ashton later today by phone, the ISNA news agency reported, adding: "The talks on implementing the accord are not easy. They are progressing, but slowly."
"I hope all sides will avoid delving into issues that could become troublesome and complicate the process," Zarif said, without elaborating, in a joint news conference with visiting Italian Foreign Minister Emma Bonino.
His deputy and chief negotiator Abbas Araqchi told ISNA the phone call "will be on serious differences of opinion over the implementation of the deal".
Neither Araqchi nor Zarif gave any other details.
Nearly a month ago in Geneva, Iran and world powers reached a deal that is meant to buy time for a diplomatic solution to a decade-long stand-off over Tehran's controversial nuclear ambitions.
Under the accord, Iran agreed to roll back or freeze parts of its nuclear drive for six months in exchange for modest sanctions relief and a promise by Western powers not to impose new sanctions.
The technical talks in Geneva are on setting out a framework and timeline for implementing the deal.
Western powers suspect Iran's nuclear activities mask military objectives, despite repeated denials in Tehran that they are entirely peaceful.
