Eighteen people are confirmed dead following protests which erupted in towns in the east of the country, Adisu Arega, spokesperson of the Oromia regional government, told the BBC.
He said 12 of the dead were ethnic Somalis while the remaining six were Oromos.
The spokesman said that the trouble began when a special unit of police from the neighbouring Somali region arrested officials from Oromia, who were then killed.
This sparked protests and clashes between the two communities in eastern Ethiopia.
Over the past few weeks there have been clashes in several villages on both sides of the border separating Ethiopia’s Oromia and Somali regions.
The spokesperson of the Oromia regional government alleged that a special police and militia force of the Somali regional government as well as armed soldiers from the republic of Somalia had carried out killings deep inside Oromia region.
Officials on the other side of the regional border have a very different view on the events.
Mohammed Bile, an adviser of the Somali regional state president, told the BBC that the Oromo regional police were carrying out attacks against civilians at the regions common border.
“They are targeting unarmed peaceful Somali civilians in those areas,” he said.