Ethiopian Prime Minister Abiy Ahmed has given the regional forces of the northern Tigray province a 72-hour ultimatum to surrender before the military begins an assault on the regional capital, Mekelle.

"We urge you to surrender peacefully within 72 hours, recognizing that you are at the point of no return," said the Nobel Peace Prize laureate in a tweet.

Earlier Sunday, the Ethiopian army threatened to besiege the city of hundreds of thousands.

"The next decisive battle is to surround Mekele with tanks," Dejene Tsegave, a military spokesman, told state broadcasters.

"Save yourself," Dejene warned Mekele residents. "A directive has been communicated for you to dissociate yourself from this junta, after that there will be no mercy."

Debretsion Gebremichael, leader of the Tigray People's Liberation Front (TPLF), has promised "fierce fighting" to halt the advance of the Ethiopian army. "They'll continue to pay for every move," he told news agency Agence France-Presse.

Escalating conflict

The TPLF led the overthrow of Mengistu Hailemariam, who headed Ethiopia's military Derg regime, in 1991. The forces subsequently dominated the political scene in the East African nation until Abiy became prime minister in 2018.

The feud with Abiy caused the TPLF to hold their own elections earlier this year, despite the postponement of national polls due to the COVID-19 pandemic. Tensions flared after an alleged TPLF attack earlier this month.

Abiy responded by taking several towns with aerial bombardments and ground fighting. The conflict has already killed hundreds, potentially thousands of people, and sent more than 30,000 refugees into neighboring Sudan.

Abiy's government has categorized the TPLF as a criminal administration and has refused all calls for peace.

World taken aback

The African Union said Saturday that it would send a special envoy to mediate between the Ethiopian government and the TPLF, an announcement Abiy called "fake news."

Susan Rice, the former US ambassador to the United Nations and US national security adviser who served in the Obama administration, tweeted Sunday that if Abiy went through with his planned assault on Mekelle it would amount to "war crimes." Rice referenced Human Rights Watch researcher Laetitia Bader in the tweet.

The US and UN have called the worsening situation in Ethiopia a looming humanitarian disaster. The UN has called for opening humanitarian corridors to allow access for aid agencies, and said it was preparing for as many as 200,000 refugees to flee into Sudan in the coming months.

kbd/aw (AP, AFP, dpa, Reuters)