Ethiopia’s human rights commission has said it will send a team to investigate reports of mass killings of civilians in the northern Tigray state.
The commission, appointed by the government but independent, said it was aware of reports of “ethnic profiling” being undertaken in the area.
PM Abiy Ahmed has accused forces loyal to Tigray’s leaders of the massacre. Its officials have denied involvement.
The UN human rights chief warned the killings could amount to war crimes.
Michelle Bachelet called for an inquiry into reports that scores and maybe hundreds of people had been stabbed and hacked to death in Mai-Kadra (May Cadera), a town in the South West Zone of Tigray.
There have been long-standing tensions between Ethiopia’s government and the Tigray People’s Liberation Front (TPLF), which controls Tigray, the country’s northernmost state.
Prime Minister Abiy ordered a military operation against the TPLF earlier this month after he accused them of attacking a military camp hosting federal troops – claims the TPLF also deny. There have since been a number of clashes and air strikes in Tigray.
The conflict has forced thousands of civilians to cross the border into Sudan, which says it will shelter them in a refugee camp.
What happened in Mai-Kadra?
The human rights group Amnesty International, said it had confirmed that “scores, and likely hundreds, of people were stabbed or hacked to death in Mai-Kadra (May Cadera) town” on 9 November.
It said it had seen and “digitally verified gruesome photographs and videos of bodies strewn across the town or being carried away on stretchers”.
Amnesty said the victims appeared to be labourers not involved in the conflict. It is not clear where they came from.
Witnesses had spoken of wounds “inflicted by sharp weapons such as knives and machetes”, Amnesty said.
Getting independently verified information about the clashes is hard because phone lines and internet services are down.
How have the opposing sides responded?
Mr Abiy said that fighters backing the TPLF went on the rampage after federal troops had “liberated” the western part of Tigray, “brutally” killing innocent civilians in Mai-Kadra.
Some witnesses also said the attacks were carried out by forces loyal to the TPLF after they had been defeated by federal troops in an area called Lugdi.
Tigray leader Debretsion Gebremichael told AFP news agency that the accusations were “baseless”.
In a statement, the Tigray government denied that its forces were behind Monday’s killings.
It added that it would welcome and co-operate with an independent international investigation into the incident.
The UN has said that vital aid supplies to hundreds of thousands of people in northern Ethiopia are at risk because of the conflict there.
What is life like in Tigray?
By Hana Zeratsyon, BBC Tigrinya
Communication is difficult at the moment because internet and mobile phone services have been cut.
There are already reports of a shortage of flour and fuel – and, worst of all, water, which was already rationed.
In Mekelle, which has a population of between 400,000 and 500,000, homes used to get piped water once a week, but the supply has stopped.
Families used to buy water from vendors, but with phones disconnected they can no longer call to put in orders.
On Thursday it was reported that a power-generating dam had been damaged in an air strike, cutting electricity supply in the region.
I am anxious about the safety of my family, especially 11-year-old brother who is suffering from cerebral palsy and epilepsy.
I am extremely worried about whether he will get his medication.
As he cannot talk, I used to see him during video calls but that is now not possible.
Read more about life in Tigray