Ethiopia said Saturday that forces loyal to the ruling party in the northern Tigray region had fired into neighbouring Amhara region, raising fears that ongoing fighting could draw in other parts of the country.

The United Nations warned Friday of possible war crimes in Ethiopia's northern region of Tigray, after 10 days of fighting that the country's prime minister claimed had his enemy "in the final throes of death".

Hundreds of Ethiopians gathered Thursday to donate blood for troops fighting in the northern Tigray region, as officials tried to rally support for a week-old conflict Prime Minister Abiy Ahmed said was going his way. 

Up to 200,000 refugees could pour into Sudan while fleeing the deadly conflict in Ethiopia's northern Tigray region, officials say, while the first details are emerging of largely cut-off civilians under growing strain. Already at least 6,000 people have crossed the border.

Long lines have appeared outside bread shops in the Tigray region, and supply-laden trucks are stranded at its borders, the United Nations humanitarian chief in the country told The Associated Press in an interview.

The end of military operations in Ethiopia's northern region of Tigray is "coming within reach", Prime Minister Abiy Ahmed said on Tuesday, as the military claimed to have captured an airport.

Ethiopia's upper house of parliament has voted to set up a transitional administration in the country's Tigray region, where fighting erupted this week between regional forces and those of the federal government.

The House of Federation's move on Saturday paves the way for the removal of the northern Tigray region's leadership that Ethiopia's federal government considers illegal. The decision needs no further approval, and it gives Prime Minister Abiy Ahmed the power to coordinate and carry out the measures.

UN chief Antonio Guterres called on Friday for the immediate de-escalation of tensions in northern Ethiopia where fighting has erupted between federal forces and troops in the Tigray region.

Ethiopian Prime Minister Abiy Ahmed said Friday that military operations launched in the northern region of Tigray had limited objectives, as concern mounts over a possible slide into war.

Ethiopia's government Wednesday declared a state of emergency in Tigray after Prime Minister Abiy Ahmed ordered a military response to a deadly attack by the ruling party of the restive region on a federal troop camp.

Ethiopia vowed Saturday not to "cave in to aggressions of any kind" after US President Donald Trump lashed out over the country's Nile River mega-dam and suggested Egypt might destroy it.

Prime Minister Abiy Ahmed's office defended the Grand Ethiopian Renaissance Dam, set to become Africa's largest hydropower plant, and said Ethiopia was working to resolve longstanding issues over the project with downstream neighbours Sudan and Egypt.