Security forces are also pursuing another 24 people from the Somali region.
More than 100 people have been arrested in Ethiopia over a string of clashes earlier this year between two of the country's largest ethnic groups that killed hundreds, the state-run broadcaster reported.
Five people from the Somali region and 98 from the Oromia region were detained on suspicion that they were involved in the violence along the border between the two federal regions, Fana Broadcasting Corporate said Saturday, citing government spokesman Negeri Lencho.
The Somali and Oromo people, who predominate these regions, are among Ethiopia's largest ethnic groups, and the fighting between them displaced tens of thousands and led to the deployment of troops to quell the bloodshed.
"The government of Ethiopia, in partnership with residents of the areas, is working jointly to rehabilitate those people displaced by the conflict," Fana reported.
Security forces are also pursuing another 24 people from the Somali region who are suspected of being involved in the fighting, the broadcaster said.
It remains unclear who started the September violence, with the Oromos blaming the Somalis for killing two officials from Oromia and the Somalis accusing the Oromos of being behind an attack on a market that killed 18 traders.
The two regions have for years argued over control of arable land along their shared border, but this conflict was far more violent than in the past, with one local official in a city near the border saying 67,800 Oromos alone fled.
Earlier this month, the state-run Ethiopian News Agency reported three other regions in Ethiopia had donated 30 million birr ($1 million) to assist people displaced by the crisis.