Oromo Liberation Army denies its fighters killed over 400 Amhara civilians, the East African country's second-largest ethnic group after the Oromo.
Amnesty International has called for an investigation into a massacre of more than 400 Amhara civilians in Ethiopia's Oromia region last month, citing eyewitnesses who blamed a local rebel group for the killings.
"These horrific killings in Tole, allegedly at the hands of the Oromo Liberation Army (OLA) reveal its perpetrators' utter disregard for human life," Deprose Muchena, Amnesty's director for East and Southern Africa, said in a statement on Thursday.
"This callous massacre, which also saw women and children lose their lives, must be independently and effectively investigated," he added.
Ethiopian authorities have blamed the OLA for a number of massacres targeting Amharas, the country's second-largest ethnic group after the Oromo.
OLA has denied the accusations, saying government-allied militias were responsible for the June 18 massacre in the west of Ethiopia's most populous region, which has seen an uptick in violence in recent months.
The assault began around 9 am [local time] when armed men allegedly belonging to the OLA surrounded villages in Tole Kebele, according to nine witnesses interviewed by the human rights group.
Although the villagers alerted the authorities after the first bullets were fired, government forces, however; arrived hours after the massacre.
The attackers unleashed a campaign of summary executions of ethnic Amhara, while also looting and burning homes, in claims corroborated by satellite imagery which showed evidence of fires breaking out in the area, Amnesty said.
'Dozens of bodies piled up'
The Amnesty statement follows a call by UN rights chief Michelle Bachelet last month urging the Ethiopian authorities to conduct "prompt, impartial and thorough" investigations into the Tole killings.
Hussein, a 64-year-old man, told Amnesty he lost 22 children and grandchildren in the attack and saw dozens of bodies piled up in the area, including a newborn baby.
"They killed 42 people at one place. There was only one adult male among them, the rest were women and children," he said.
Another man told the rights group the attackers "torched the house of my neighbour while the family with his children and grandchildren and others were inside".
"One of them was seven months pregnant and was with her two children. They were buried in the compound since they were completely charred."
None of the witnesses were identified by their real names due to safety concerns, Amnesty said.
More than 300 massacred
No official toll from the massacre has been published, but Prime Minister Abiy Ahmed's spokesperson Billene Seyoum said last month that 338 victims had so far been identified.
A local administrative official told Amnesty that at least 450 people were killed in the attack.
Witnesses said they identified the attackers as OLA militants because of their uniforms, their "distinctive long braided hair", and their use of the Oromiffa language.
The gunmen also set fire to houses and looted cattle, cash and other items belonging to the villagers, Amnesty said.
Officials "said they were unable to respond because the road was closed", the watchdog said.
The OLA, a shadowy group that has been fighting the federal government in Oromia since 2018, gained new prominence last year when it struck up an alliance with Tigrayan rebels who have been at war with pro-Abiy forces in northern Ethiopia since November 2020.