A girl cooks bread in a compound of abandoned buildings, where internally displaced people are sheltered, near the town of Dubti, 10 kilometres from Semera, Ethiopia, on June 7, 2022. AFP
The New York-based watchdog said it had documented serious abuses in Ethiopia's most populous region, including in western Oromia where an "abusive" government campaign against an armed rebel group had trapped civilians in the crossfire.
This violence has persisted for years without redress while global attention has centred on Tigray, where major combat between federal forces and rebels from the region exploded in November 2020.
"Well before the conflict in northern Ethiopia, there has been widespread impunity for ongoing rights abuses in Ethiopia's Oromia region, including in areas already suffering from conflict," HRW said in a statement.
"Many of these abuses still persist and require urgent international attention."
This culture of impunity "has only emboldened unaccountable security forces and done nothing to prevent further harm", it said.
Access is restricted to western Oromia where Ethiopia's armed forces have been countering a rebellion by the Oromo Liberation Army (OLA) for years.
But summary executions and arbitrary detentions by government forces have still been documented there, HRW said, as have abductions and killings of local leaders and government officials by armed groups.
In June, hundreds of people, mostly from the Amhara ethnic group, were massacred by gunmen in the village of Tole, western Oromia.
Local authorities said the OLA was responsible, but the rebels denied any role and blamed a pro-government militia.
Earlier that month, government forces were accused of summarily executing suspected OLA collaborators in the capital of the neighbouring Gambella region following an attack on the city.
Oromia was the scene of deadly violence after the murder in June 2020 of Hachalu Hundessa, a popular Oromo singer who gave voice to the frustrations felt by many in the region.
More than 160 people were killed in street demonstrations following his death while Oromo political leaders and opposition activists were rounded up and detained in a sweeping government crackdown.
Many were later released but some remained in detention despite court orders for their release, HRW said.
"Ethiopia's government and its partners should no longer ignore the mounting tragedies affecting families throughout Oromia. There is a deep need for structural reforms of the abusive security apparatus and for social repair," HRW said.
"The government can start by facilitating credible independent investigations into the serious abuses by its own forces and by armed groups, as communities demanded."