Iran's chief nuclear negotiator says talks in Geneva have so far shown "good progress."
Iranian state television aired an interview with negotiator Abbas Araqchi on December 31 in which he said the previous day's meeting with representatives from the United States, Britain, France, Russia, China, and Germany -- the so-called P5+1 group -- stretched until 4:30 a.m.
Araqchi said there would be another meeting later on December 31.
Negotiations on a framework to implement last month's nuclear deal with Iran resumed after a weeklong break.
Two rounds of talks have been held since November 24, when Iran agreed to suspend parts of its disputed nuclear program for six months in return for limited sanctions relief, while a longer-term agreement is forged.
Based on reporting by AFP and Interfax