Gunmen have killed at least 42 people in Ethiopia's Oromia region, reported two residents who buried the bodies in mass graves; during the latest wave of killings in the country's most populous region, where escalating violence has claimed hundreds of lives.

The two witnesses said that the attack, carried out by an armed group against civilian residents, took place last Tuesday, in the Amuro district, 370 km west of the capital, Addis Ababa.

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Yesterday, on Thursday, the Tigray People's Liberation Front announced that the Ethiopian government forces, in conjunction with Eritrean forces, began implementing a joint campaign against the region, in light of the military actions between the two sides.

"The enemy - the government forces - has launched a joint campaign with a huge military force from Eritrea in order to exterminate the Tigray people," the Tigray Regional Office of Foreign Affairs said in a statement.

A few days ago, the Tigray Liberation Front and the Ethiopian government exchanged accusations of returning to hostilities, about 5 months after the declared humanitarian truce took effect.

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