Egyptian opposition leaders on Friday rejected a national dialogue that President Mohammed Mursi had proposed as a way out of a crisis that has polarised the nation and provoked deadly clashes on the streets.   Opponents of Mursi staged more protests in Cairo and other cities, while his supporters in the Muslim Brotherhood held emotional funerals for six of the movement’s members killed in fighting around the presidential palace earlier in the week.     Mursi had offered few concessions in a speech late on Thursday, refusing to retract a Nov. 22 decree in which he assumed sweeping powers or cancel a referendum next week on a constitution newly drafted by the assembly.     Instead, he called for a dialogue at his office on Saturday to chart a way forward for Egypt after the referendum, an idea that liberal, leftist and other opposition leaders rebuffed.     They have demanded that Mursi rescind the decree in which he temporarily shielded his decisions from judicial review and that he postpone the Dec.15 referendum before any talks begin.