The leader of Ethiopia's dissident Tigray region said Monday that his people were "ready to die" defending their homeland, rejecting Prime Minister Abiy Ahmed's ultimatum that they surrender within 72 hours.

Abiy launched a military campaign against the Tigray People's Liberation Front (TPLF) on November 4, accusing it of attacking two federal military camps in the northern region, as well as defying and seeking to destabilise his government.

The federal army says its forces are within 60 of Mekele, the Tigrayan capital and seat of the TPLF, ahead of a threatened all-out bombardment of the city of half a million people.

Abiy, last year's Nobel Peace Prize winner – on Sunday called on the TPLF to surrender peacefully within three days, saying they were "at a point of no return".

But the TPLF's leader Debretsion Gebremichael said Abiy was trying to cover for setbacks his army had suffered against Tigrayan forces, and was issuing threats to buy time.

A communications blackout in the region has made claims from both sides difficult to verify.