Ethiopia's prime minister said on Thursday the army has been ordered to move on the embattled Tigray regional capital after his 72-hour ultimatum ended for Tigray leaders to surrender, and he warned its half-million residents to stay indoors and disarm.

The military offensive "has reached its final stage" after three weeks of fighting, Prime Minister Abiy Ahmed's office said. That means tanks and other weaponry can close in on Mekele, whose residents had been warned of "no mercy" if they didn't move away from Tigray leaders in time.