UN warns of war crimes in spiralling Ethiopia conflict

The United Nations warned Friday of possible war crimes in Ethiopia's Tigray region, as the US condemned the massacre of civilians in fighting which the prime minister claimed had left his enemy "in the final throes of death".

Prime Minister Abiy Ahmed, winner of last year's Nobel Peace Prize, ordered military operations in Tigray last week, shocking the international community which fears the start of a long and bloody civil war.

Hundreds of people are reported to have been killed, some in a gruesome massacre reported by Amnesty International, and thousands have fled fighting and air strikes in Tigray, whose leaders Abiy accuses of seeking to destabilise the country.

The United States urged an immediate de-escalation.

"We condemn the massacre of civilians in Mai-Kadra and strongly urge immediate steps to de-escalate and end conflict throughout the Tigray region," said Tibor Nagy, the top US diplomat for Africa, referring to a town where Amnesty International reported mass killings.

UN rights chief Michelle Bachelet called for a full investigation into the report of mass killings in Mai-Kadra, where Amnesty said it had "digitally verified gruesome photographs and videos of bodies strewn across the town or being carried away on stretchers".