By Anne Soy
Senior Africa correspondent
An 11-year-old Ethiopian girl describes spending the night outside after fleeing fighting in Tigray.
The prime minister was left with no option but to respond with force, the attorney general says.
BBC News, Addis Ababa
Ethiopia's Prime Minister Abiy Ahmed has met an African Union mission that arrived in Addis Ababa to try to mediate between his government and the Tigray People's Liberation Front (TPLF) after more than three weeks of military conflict.
Mr Abiy previously branded international efforts to bring the two parties to the table as "unwelcome", and the AU mission will not be allowed to meet Tigray officials.
After Friday's meeting with three special AU envoys, Mr Abiy said in a statement that his government was seeking to ensure the protection of civilians, it was opening a humanitarian corridor, and it will welcome back Ethiopian refugees who fled into Sudan.
However, the prime minister said his government would continue its efforts against what it calls the "TPLF clique".
The AU envoys - ex-presidents Joaquim Chissano of Mozambique, Ellen Johnson Sirleaf of Liberia and Kgalema Motlanthe of South Africa - will not be allowed to travel to Tigray, the government has already said.
Ethiopia's presidency has thanked the "esteemed African elders" for their "readiness to support". But it's not clear how the envoys can accomplish their mission without meeting both sides.
BBC World Service
The leadership in Ethiopia's Tigray region says it has appointed a representative to discuss with the African Union (AU) and other international bodies an immediate cessation of hostilities with the Ethiopian government.
In a statement, it also called for unimpeded humanitarian access and an independent investigation into any alleged war crimes.
Prime Minister Abiy Ahmed is due to meet AU peace envoys, but has rejected international mediation in the conflict.
Fighting is reported between Tigrayan forces and government troops in several areas of Tigray, but the regional capital Mekelle is said to be calm.
Ethiopia says an assault on the regional capital Mekelle will target only Tigray's "treasonous" leaders.
One of the researchers behind this week's report by the Ethiopian Human Rights Commission (EHRC) into mass killings in the Tigray region has been speaking to the BBC about what she saw.
The town of Mai-Kadra witnessed a massacre earlier this month as the conflict between the federal army and those loyal to the Tigray People's Liberation Front (TPLF) escalated.
Rights groups, including Amnesty International, said that hundreds may have died, and the UN warned that the killings could constitute a war crime.
After an investigation, the EHRC, a constitutional body, said that more than 600 people had died and it accused a youth group from Tigray region of being behind the killings.
The commission says the group stabbed, bludgeoned and burned to death non-Tigrayan residents, which the TPLF denies.
The EHRC's Haimanot Ashenafi told the BBC that the "stench of decomposing bodies in the town was unbearable".
"Seeing dead bodies on the road is depressing," she added.
The town is now deserted and she said that the shoes of the deceased can be seen everywhere.
She said that because of the large numbers of dead, the burials were not done as they should have been.
Ethiopia's Deputy Prime Minister Demeke Mekonnen has continued his diplomatic mission in Africa and Europe to present his government's position on the conflict in the Tigray region.
Pictures published by the state-affiliated Fana Broadcasting Corporate show him meeting French President Emmanuel Macron in Paris.
That meeting came shortly after Prime Minister Abiy Ahmed announced that the fighting Tigray was in its final phase.
Despite pressure from outside, Ethiopia has resisted international calls for negotiations with the Tigray People's Liberation Front (TPLF).
Mr Demeke told the French president that the government had tried to resolve differences with the TPLF through discussion, but it had "repeatedly committed evil acts, causing harms to the public and the government", Fana reports him as saying.
There is no statement yet from the French president's office.
On Monday, Mr Demeke met Britain's foreign minister, he has also held discussions with the presidents of Uganda and Kenya.
Africa editor, BBC World Service
As we've been reporting Ethiopia's Prime Minister Abiy Ahmed has ordered the military to launch what he describes as its final offensive against dissident leaders in the northern region of Tigray.
But how long is this stage of the fight going to last?
Forces loyal to the leadership in Tigray say they will never surrender - indeed one said it would be a taboo to do so.
Mr Abiy says there is a "carefully devised" strategy to ensure civilians will not be harmed in the fight for the regional capital, Mekelle.
But rights groups have warned that bombarding this city of half a million could constitute a war crime.
While some civilians have fled, the vast majority remain - and are likely to face violence in the coming hours or days.
With tens of thousands of people fleeing the fighting in northern Ethiopia and crossing into Sudan Ethiopia's federal government has come under a lot of pressure from humanitarian agencies.
There has been concern that a humanitarian disaster is unfolding.
In a message from Prime Minister Abiy Ahmed's office, the government says that it is supporting those in need in Tigray and will set up camps to receive those who have fled.
The government will also open up what is described as a "humanitarian access route".
The statement said that the authorities are "committed to work with UN agencies and other.... organisations".
The BBC's Anne Soy reaches a refugee camp where aid agencies say they are struggling to provide help.
BBC News, Addis AbabaCopyright: Getty Images
An Africa Union mission has arrived in Ethiopia's capital, Addis Ababa, to try to mediate between the federal government and the northern Tigray state after three weeks of conflict.
Three former African heads of state - Joaquim Chissano of Mozambique, Ellen Johnson Sirleaf of Liberia and Kgalema Motlanthe of South Africa - form part of mission.
Their arrival coincides with what Prime Minister Abiy Ahmed has called the "final phase" in the operation in Tigray.
Mr Abiy has already rejected international efforts to negotiate a peaceful end to the fighting, describing it as a "law-enforcement operation".
The conflict has already displaced tens of thousands into neighbouring Sudan and left scores dead.
Ethiopia's Prime Minister Abiy Ahmed has said federal troops have begun the final phase of the operation in the northern Tigray state.
In a statement, he said "great care" would be taken to protect the 500,000 inhabitants of the region's capital, Mekelle, from harm.
But Mr Abiy warned residents to stay indoors.
He said that thousands of Tigrayan forces and militia had surrendered in the last 72 hours - but Tigray officials are yet to respond to the claim.
It has been difficult to verify claims from either side because of a communications blackout.
Mr Abiy had given Tigray forces a deadline to peacefully surrender which ended on Wednesday.
He rejected international interference in Ethiopia's internal issues and said the Tigray situation would be resolved in accordance to laws and international obligations.
The UN had asked the Ethiopian government to protect civilians ahead of the assault on Mekelle.
By Peter Mwai and Christopher Giles
BBC Reality Check
Ethiopian troops have been deployed along the border with Sudan and are having an impact on the flow of refugees, according to people fleeing the northern state of Tigray.
This comes in the middle of a military confrontation between the federal government and the region's dominant party, the Tigray People's Liberation Front (TPLF).
The UN has expressed fears about the safety and welfare of civilians.
The Ethiopian government said it will make a final push into the regional capital, Mekelle, as a new deadline for the TPLF fighters to surrender lapsed on Wednesday.
The BBC's Anne Soy, who is on the Sudan side of the border, says River Sittet in Hamdayit has been an important border crossing point for people fleeing fighting in Tigray.
The Sudanese Commission for Refugees said it had been receiving an average of 1,200 people there daily.
On Wednesday our reporter saw at least a dozen soldiers stationed on the hills across the river. The refugees identified them as Ethiopian federal forces and said they had been stopping people crossing into Sudan.
The federal government has not responded to the BBC’s request for comment.
Many refugees who have been waiting for their relatives to join them in Sudan are worried about this new development.
BBC World Service
Three former African leaders are expected in Ethiopia as an ultimatum for northern Tigrayan forces to surrender is due to expire.
The Prime Minister Abiy Ahmed says he will meet the African Union envoys but has described international efforts to bring an end to the conflict as unwelcome, unlawful interference.
Ethiopian forces are poised for an assault on Tigray's capital, Mekelle, once Wednesday's deadline expires.
Ethiopian troops at a major border crossing into Sudan are said to be preventing refugees from leaving the country.
Hundreds of people have reportedly been killed and thousands have been forced from their homes since the conflict began three weeks ago.
BBC News, Nairobi
Reports from northern Kenya say Ethiopian troops have staged a cross-border raid into the town of Moyale, hunting for supporters of a rebel group.
Witnesses said neighbourhoods were ransacked and 10 Kenyans dragged away, accused of sheltering members of a splinter group of the Oromo Liberation Front.
OLF Shane group, which has been blamed for a series of attacks and killings in western and southern Ethiopia.
Residents allege Kenyan security officers looked on, as the young men were dragged away across the border.
Neither the Kenyan nor the Ethiopian government have made any comments on this alleged incursion into Kenyan territory.
The Ethiopian military is currently conducting an operation against members of the group in Southern and Western Ethiopia. Heavy fighting has been heard in areas bordering Kenya over the last few weeks.
Early this month, armed men from the OLF Shane group killed 60 people and torched more than 20 houses in a raid in western Ethiopia.
The OLF Shane split from the Oromo Liberation Front (OLF), a once exiled opposition group, that was allowed back to Ethiopia after Prime Minister Abiy Ahmed took power in 2018.