Separatist rebels in Ethiopia's Ogaden region say days of air attacks on civilians have caused many casualties.
Helicopter gunships have been used to attack villages in the remote area, says the Ogaden National Liberation Front (ONLF).
Aid workers say an estimated 1,500 Ogaden refugees crossed into Kenya to escape renewed fighting last month.
Ethiopia has not commented but last week, the army said it had killed some 100 rebels in the past month.
Since April, when rebels attacked a Chinese oil exploration unit killing 74 people, the Ogaden has been the scene of continuous clashes.
International agencies, including the Red Cross, have been expelled from the Ogaden and there is little chance of independently verifying the conflicting claims from the government and rebels.
Ogadenis fleeing into northern Kenya have given harrowing description of government assaults on their villages.
More than 500 families reached different parts of Kenya's massive Dadaab camps in October - many gave similar accounts of a sustained campaign of rape and brutality, with men hanged from trees.
In separate interviews reported by the Reuters news agency, the Ogadenis claimed Ethiopian soldiers had been entering villages over and over again to kill, rape and burn in a campaign to flush out ONLF rebels.
Ethiopia has dismissed similar accounts as "rebel propaganda".
The ONLF, founded in 1984, says it is fighting for the rights of the local Somali-speaking population.