TEHRAN - Iran and six world powers will continue their expert-level nuclear talks after the Christmas holidays, Iran's nuclear negotiator said Monday.

"The technical and expert-level negotiations (paused on Sunday after four days of talks in Geneva) will continue one week after Christmas holidays," Abbas Araqchi said, according to state IRIB TV.

The decision was made after Iranian Foreign Minister Mohammad Javad Zarif and European Union foreign policy chief Catherine Ashton had a telephone conversation on Sunday, Araqchi said, adding that in the 45-minute conversation, some differences were also reviewed by the two sides.

There was "little progress in the talks" which started on Thursday, Araqchi said, adding that different interpretations of an earlier interim deal has been the reason for the slow progress.

The expert-level talks between Iran and the P5+1 group -- United States, Britain, France, Russia, China plus Germany -- are aimed at implementing the deal struck in Geneva on November 24, in which Iran agreed to freeze part of its nuclear program in exchange for limited ease of sanctions which had hurt its economy.

On Sunday, Zarif said the talks were advancing slowly since " the talks are not easy and the details should be discussed accurately."

Last week, Iran quit the expert-level meeting in protest of the United States' blacklisting of additional individuals and companies allegedly violated existing Western sanctions against Iran.