Fighting between rival ethnic groups in western Ethiopia has killed at least 44 people and displaced 70,000, the UN says.

Violence erupted on Friday after gunmen killed four local officials during a visit to neighbouring Oromia region, residents of Benishangul-Gumuz say.

Youths armed with rocks and knives forced people to flee their homes.

Prime Minister Abiy Ahmed's push for reforms since coming to office in April has failed to quell ethnic conflicts.

Benishangul-Gumuz, which borders Sudan and South Sudan, is one of Ethiopia's nine regional states.

Nearly one million people have been displaced in southern Ethiopia since clashes erupted there in April, according to UN agencies.

The people behind the killing at the border between Oromia and Benishangul-Gumuz regions were unidentified gunmen, Benishangul-Gumuz's communications chief Zelalem Jaleta was quoted as saying by Walta Media, which is close to the governing party. (BBC)