The main Syrian opposition meeting in the Saudi capital Riyadh said on Thursday they rejected any role for Syrian President Bashar al-Assad at the start of a U.N. sponsored interim period leading to a political transition, according to a communique. "The participants stressed that this (the transition) cannot happen without the departure of Bashar al Assad and his clique at the start of the interim period," the communique said at the end of the meeting of opposition.