NEW : 100,000 people were killed Saturday , a Iranian opposition group says . Syria says its military killed terrorists who were attacking orchards . Saturday may have been the deadliest day of the conflict . There could be At least 143 deaths in Syria Sunday , envoy says .
NEW : At least 143 people were killed Sunday , a Syrian opposition group says . Syria says its military killed terrorists who were attacking orchards . Saturday may have been the deadliest day of the conflict . There could be 100,000 deaths in Syria next year , envoy says .