The foes kicked off preliminary negotiations last week in Tanzania, meeting in the semi-autonomous region of Zanzibar for what OLA spokesman Odaa Tarbii described as "initial talks... intended to establish a foundation for more extensive discussions".

The OLA, an armed insurgent movement from the country's Oromia region, has been fighting Addis Ababa since it split in 2018 from the Oromo Liberation Front (OLF) when that group renounced armed struggle.

"The first round of the peace talks held in Tanzania concerning the conflict in the Oromia regional state have been concluded today," the Ethiopian government communications service said in a statement released Wednesday.

"While the talks have been largely constructive, unfortunately, it was not possible to reach an agreement on some issues during this round of the talks," it said, without elaborating on the sticking points.

It added however that "both parties have acknowledged the need to continue these talks with a view to resolving the conflict permanently and peacefully."

The OLA did not respond to AFP's requests for comment.

Since the OLA broke off from the OLF and started fighting, a string of armed groups in Oromia have risen up claiming to be part of its cause, although they are only loosely tied.

The OLA's strength, estimated at a few thousand men in 2018, has increased significantly in recent years, though observers believe it is insufficiently organised or well-armed to pose a real threat to the federal government.

Oromia surrounds Addis Ababa and is Ethiopia's largest and most populous region, and has suffered ethnic massacres in recent years carried out by unknown groups.

The OLA has been repeatedly accused by Prime Minister Abiy Ahmed's government of being responsible for the killings, a charge it denies.

The government is accused of waging an indiscriminate crackdown that has fuelled Oromo resentment against the central government.