The Ethiopian government has given the Tigray People's Liberation Front (TPLF) 72 hours to surrender and end its rebellion.

The conflict has entered its “final” phase, with the next major offensive focusing on the Tigray region’s capital, Mekele, where the rebels are hiding out, Prime Minister Abiy Ahmed’s office said in a statement on Sunday.

The statement comes a day after government forces captured Adigrat, the second-largest city in Tigray.

The African Union (AU) Saturday said it will send a special envoy to mediate between the government and the TPLF, the region's ruling political party, now designated as a rebel group.

Abiy has however described the announcement as “fake news.”

The conflict between the Ethiopian government and Tigray began earlier this month when Abiy deployed troops to put down an uprising by the TPLF.

The unrest has already led to tens of thousands of Ethiopians fleeing towards neighbouring Sudan.

The UN Refugee Agency (UNHCR) is preparing for 200,000 arrivals from Ethiopia in Sudan, up from the current 33,000.