International pressure mounted yesterday on the warring parties in northern Ethiopia to cease fighting and protect civilians in Tigray, whose leaders Prime Minister Abiy Ahmed has given a deadline to surrender. 

The UN Security Council was to convene its first meeting on Tigray later yesterday, where forces loyal to the region's ruling party have been battling Ethiopian soldiers for nearly three weeks, sparking a refugee exodus, civilian deaths and fears of broader instability in the Horn of Africa.

Abiy, last year's Nobel Peace Prize winner, ordered troops, tanks and warplanes into Tigray on November 4 in response to an alleged attack on federal military camps by the Tigray People's Liberation Front (TPLF).

The army says it has encircled Mekele, the regional capital, ahead of a threatened all-out assault.

The prime minister, who has resisted calls for mediation and insists the conflict has reached a decisive final stage, on Sunday gave the TPLF 72 hours to surrender -- an ultimatum rejected by the dissident region's leader, who says his people are "ready to die" for the homeland.

The prospect of a devastating bombardment of Mekele, a city of half a million people and a refuge for many more fleeing the conflict, has alarmed rights groups who warn such an attack on a civilian centre could contravene international law.

The fighting has already driven more than 40,000 people into Sudan and reportedly killed hundreds and forced many more to flee within Tigray, though the true extent of death and displacement is not yet known.

A communications blackout and restrictions on reporting in the region have made claims from both sides difficult to verify.

The TPLF on Monday said it routed an army battalion and claimed responsibility for a rocket attack on Bahir Dar, the capital of Amhara region to the south of Tigray, whose local forces are fighting alongside Ethiopian troops. The government said that "a large number of Tigray militia and special forces are surrendering" following the issuance of Abiy's 72-hour ultimatum.

Long-running tensions between Addis Ababa and the TPLF, which dominated Ethiopia for nearly three decades before Abiy came to power in 2018, boiled over in September when Tigray proceeded with regional elections in defiance of the federal government, which declared the vote illegal.