NEW : The head of the Syrian National Council warns the regime is planning a coup . NATO : He calls on allies to act outside of the U.N. Security Council . NEW : At least 20 people are killed across Syria on Saturday , including an opposition group . Kofi Annan expresses concern for an ` ` imminent attack '' in Syria 's largest city .
NEW : The head of the Syrian National Council warns the regime is planning a massacre . NEW : He calls on allies to act outside of the U.N. Security Council . NEW : At least 160 people are killed across Syria on Saturday , says an opposition group . Kofi Annan expresses concern for an `` imminent battle '' in Syria 's largest city .