Ethiopia's Prime Minister Abiy Ahmed gave the leaders of a dissident northern region 72 hours to surrender ahead of a threatened all-out assault on Tigray's capital, Mekele.

Abiy -- last year's Nobel Peace Prize winner -- launched the military campaign against the Tigray People's Liberation Front (TPLF) on November 4, accusing it of attacking two federal military camps in the region, and of defying his government and seeking to destabilise it.

A communications blackout in the region has made claims from both sides difficult to verify but hundreds of people are reported to have been killed while tens of thousands have fled the fighting into neighbouring Sudan.

TPLF have destroyed an airport in the ancient town of Axum, state-affiliated media said yesterday.

"Your journey of destruction is coming to an end, and we urge you to surrender peacefully within the next 72 hours, recognising you are at a point of no return," Abiy said on Sunday night in a statement aimed at the leaders of the TPLF party.

"Take this last opportunity," he added.

Abiy also called on the TPLF forces to "surrender peacefully" and urged the people of Mekele to side with the army "in bringing this treasonous group to justice"

Earlier in the day, the Ethiopian army had threatened to besiege the city of half a million and warned civilians to flee while they still could.

"The next decisive battle is to surround Mekele with tanks," Dejene Tsegaye, a military spokesman, told state broadcasters.