United Nations Secretary General Ban Ki-moon acknowledged progress has been slow in arranging international peace talks aimed at ending Syria's civil war.
Mr. Ban said Wednesday key elements of the U.N.-sponsored talks are still undecided, including whether the Syrian opposition will attend and who would represent it.
Earlier, Syrian opposition leaders repeated a demand for President Bashar al-Assad to leave power, saying they will not agree to the talks without a timetable for his withdrawal.