Ethiopian Prime Minister Abiy Ahmed on Friday met with African Union envoys to discuss the conflict in Tigray, where the army is poised for what he has called the final offensive against regional forces.
Abiy, the winner of last year's Nobel Peace Prize, on Thursday announced a "third and final phase" in his campaign against the Tigray People's Liberation Front (TPLF), whose forces have been battling federal troops in the defiant northern region for three weeks.
The violence has killed many hundreds and displaced tens of thousands more, but there are grave fears for half a million civilians in Mekele, the regional capital, which the army says it has encircled ahead of a threatened attack.
The international community has warned such a strike could violate rules of war and has called for urgent mediation.
The federal government launched a military campaign on November 4 after months of friction between Addis Ababa and the TPLF, which governs Ethiopia's northernmost region.
Abiy has refused to negotiate with the TPLF and rebuffed calls for dialogue as "interference" in Ethiopia's internal affairs.
But the prime minister received at his office in Addis Ababa on Friday three African ex-leaders -- Joaquim Chissano of Mozambique, Ellen Johnson Sirleaf of Liberia and Kgalema Motlanthe of South Africa -- dispatched this week by the AU as mediators.
In a statement issued after their meeting, Abiy said he appreciated "this gesture and... the steadfast commitment this demonstrates to the principle of African solutions to African problems."
Even so, the government has a "constitutionally mandated responsibility to enforce rule of law in the region and across the country," he said.
Many attempts, he added, had been made to negotiate with the TPLF before military action was ordered on November 4.
Pope Francis was concerned about the intensifying fighting, growing loss of life and people fleeing their homes, Vatican media head Matteo Bruni said.
"The Holy Father appeals to the parties in the conflict to stop the violence, save lives, especially civilians, so that the populations can find peace again," Bruni said in a statement.
The Tigrayan government, meanwhile, said the federal army was bombarding towns and villages and inflicting heavy damage, although it did not specifically mention Mekele.
"Our struggle will continue from every direction until the self-determination of the People of Tigray is guaranteed and the invading force is driven out," the authorities said in a statement read on local television, Tigray TV.
It called upon "the Tigray people as usual to struggle and defend" themselves.
The conflict has erupted in a year when the 55-member AU -- which is headquartered in Addis Ababa -- resolved to play a more prominent role in resolving conflicts across the continent under the slogan "Silencing the Guns".
The AU called for an immediate halt to hostilities on November 10 but the conflict only spiralled further, with warplanes bombing the mountainous region and both sides claiming the upper hand.
Tigray has been under a communications blackout since fighting began, making it difficult to weigh competing claims about casualties, and who holds what territory.
It was unclear Friday whether the attack on Mekele had begun, or how close federal forces were to the city.
The state-affiliated Ethiopian Broadcasting Corporation said late Thursday the army -- which in recent days said it was advancing on Mekele with tanks -- had identified key TPLF hideouts across the city, including an auditorium and a museum.
Abiy, who ordered the strike on TPLF forces in Mekele after the lapsing of a deadline for their surrender, said "great care" would be taken to protect innocents and spare the city from severe damage.
The prospect of a full-scale attack accelerated diplomatic efforts this week to resolve the conflict, with the UN Security Council holding its first meeting on Tigray and US and European officials urging restraint.
French Foreign Minister Jean-Yves Le Drian, who met his Ethiopian counterpart Demeke Mekonnen in Paris on Thursday, called for urgent measures to protect civilians as the humanitarian fallout from the crisis worsens across the region.
The UNHCR said Friday that nearly 100,000 Eritrean refugees in Tigray could run out of food as early as Monday if supplies cannot reach them.
In eastern Sudan, meanwhile, where more than 40,000 refugees have escaped the fighting in Tigray, local authorities are struggling to meet the sudden surge in demand for food, shelter and other life-saving essentials.
The UNHCR said Friday that a plane carrying 32 tonnes of emergency aid had arrived in Sudan, and another airlift with 100 tonnes was expected Monday.
Refugees crossing the border said those still trying to reach Sudan were cutting across fields to avoid detection by Ethiopian troops, who they said were blocking the main exit route from Tigray.
Abiy ordered the military into Tigray after alleged attacks by TPLF forces on federal army camps in the region.
The TPLF dominated Ethiopian politics and controlled its security for the better part of three decades until Abiy rose to power in 2018, beginning a power struggle between the former rulers and the new leader.