Abiy late Sunday gave the Tigray People's Liberation Front (TPLF) 72 hours to surrender
Prime Minister Abiy Ahmed on Thursday ordered Ethiopia's army to launch a final offensive against Tigray's dissident leaders in their regional capital Mekele, saying the deadline for surrender had expired.
Abiy, the winner of last year's Nobel Peace Prize, late Sunday gave the Tigray People's Liberation Front (TPLF) 72 hours to lay down their arms.
The ultimatum was rejected by the leaders of the region, whose forces have been fighting federal troops in the country's north for three weeks, displacing over 40,000 people and killing hundreds.
Ethiopia's army -- which in recent days said it was advancing on Mekele with tanks -- had been directed "to conclude the third and final phase" against the TPLF, Abiy said.
"In this final phase, great care will be given to protect innocent civilians from harm. All efforts will be made to ensure that the city of Mekele, which was built through the hard work of our people, will not be severely damaged," Abiy said.
He said "thousands" of TPLF militia and special forces had surrendered to federal forces before the deadline lapsed.
It was not immediately clear how close the army was to the city. A communications blackout in Tigray and restrictions on reporting have made verifying claims from both sides difficult.
'Carefully devised' strategy
Diplomats briefed on the fighting told AFP Wednesday that federal forces were at least 30 kilometres from Mekele to the north and the south.
The threatened assault and fears for Tigray's half a million inhabitants accelerated diplomatic efforts this week to mediate, with the UN Security Council holding its first meeting on the crisis on Tuesday.
UN Secretary General Antonio Guterres urged "the leaders of Ethiopia to do everything possible to protect civilians" as the US, EU and other international powers encouraged mediation through the African Union, headquartered in Addis Ababa.
Amnesty International and other rights watchdogs warned bombarding Mekele could constitute a war crime.
Abiy stressed that Ethiopia's defence forces had "carefully devised" a strategy to defeat the TPLF in Mekele without harming civilians or public property.
"We call on the people of Mekele and its environs to disarm, stay at home and stay away from military targets" and assist by handing over TPLF elements in their midst, Abiy said.
Abiy, who ordered troops into Tigray on November 4 following alleged attacks by TPLF forces on federal military camps in the region, has resisted appeals for talks and his government had flatly refused to negotiate.
As international pressure mounted this week, Abiy issued a strongly-worded statement rejecting outside "interference" in what he labelled an internal "law enforcement" operation.
"We therefore respectfully urge the international community to refrain from any unwelcome and unlawful acts of interference and respect the fundamental principles of non-intervention under international law," hes said.
Since the fighting began, more than 40,000 people have fled to eastern Sudan and rockets have fallen on the Eritrean capital Asmara and Ethiopian cities outside Tigray, spurring fears the conflict could destabilize the wider Horn of Africa region.
Hundreds have reportedly been killed -- though a true figure is not known. Ethiopia's rights watchdog this week said at least 600 civilians were brutally massacred in the Tigrayan town of Mai-Kadra alone.
The TPLF led the overthrow of Ethiopia's military Derg regime in 1991 and dominated the country's politics until Abiy became prime minister in 2018.
Since then, TPLF leaders have complained of being sidelined by Abiy and blamed for the country's woes, and tensions have festered between the regional leadership and the federal government in Addis Ababa.