Iran nuclear talks aren't over yet- US official

British Foreign Secretary William Hague arrives at the Intercontinental Hotel in Geneva November 23, 2013. Iran and six world powers struggled on Friday to budge sticking points in negotiations aimed at securing an interim accord to curb Tehran's nuclear programme in exchange for sanctions relief. [Photo/Agencies] 

German Foreign Minister Guido Westerwell speaks to media after his arrival at the Intercontinental Hotel in Geneva November 23, 2013. Talks on Iran's nuclear programme were "not a done deal," Guido Westerwelle said on Saturday, as foreign ministers of six world powers gathered in Geneva for a fourth day of negotiations. [Photo/Agencies] 

Iranian Foreign Minister Mohammad Javad Zarif (C), flanked by members of his delegation, attends talks over Iran's nuclear programme in Geneva November 22, 2013. [Photo/Agencies]