The UN Security Council is due to hold its first meeting later on Tuesday to discuss the conflict in Ethiopia’s northern Tigray state.
The virtual meeting comes as the Ethiopian government says its tanks are preparing to attack the Tigrayan capital, Mekelle.
It has given the Tigray People’s Liberation Front (TPLF) forces, who control the city, until Wednesday to surrender.
TPLF forces are claiming they have “destroyed” one of the Ethiopian army’s mechanised divisions.
Nearly three weeks of fighting has left hundreds of people dead.
International agencies have warned the conflict is on the brink of a deadly escalation.
A government spokesperson in Addis Ababa has been quoted as calling on residents in Tigray’s capital, Mekelle, to leave the city or work with the government to defeat opposition forces.
Redwan Hussein said time was running out ahead of a deadline for Tigray People’s Liberation Front (TPLF) troops, who control the mountainous region, to surrender by Wednesday.
But the leader of the region, which has been fighting national forces for nearly three weeks, said his people would rather die than give up fighting.
Ethiopian authorities insist total victory in the northern Tigray state is close. They say they want to avoid a fierce fight in Mekelle – home to 500,000 people.
The conflict has reportedly killed hundreds and displaced thousands in recent weeks. The UN has warned it could trigger a humanitarian crisis.