MOGADISHU, Aug 14 (Reuters) - Heavy fighting between Somali government forces backed by Ethiopian troops and insurgents in Mogadishu has killed at least 31 Somalis and wounded 60 in the past 24 hours, a local human rights group said on Tuesday. "The killings were from gunshots and explosions in different parts of the city," head of Elman Human Rights Group, Sudani Ali Ahmed, told Reuters. "It is totally unacceptable and ... against human rights." In one incident, Ethiopian soldiers opened fire on a bus full of civilians, killing 10 people and wounding several others, Ahmed said.