Ethiopia’s leader has warned that “the final and crucial” military operation will soon be launched against the rulers of the country’s rebellious northern Tigray region.

Prime Minister Abiy Ahmed said on Tuesday a three-day deadline to surrender had expired, paving the way for a final push on Mekelle, the region’s capital.

“The final critical act of law enforcement will be done in the coming days,” Abiy said in a statement posted on Facebook.

The prime minister’s warning came after federal government forces carried out “precision-led and surgical air operations” outside Mekelle, a government emergency task force said, and ground forces pushed forward.

The Tigray People’s Liberation Front (TPLF), which governs the region, said civilians had been killed in the attacks, allegations the task force denied.

Tigray TV showed what appeared to be a bombed-out residential area with damaged roofs and craters in the ground in Mekelle.

“I heard the sound of some explosions. Boom, boom, boom, as I entered the house,” the station quoted a resident as saying. “When I got out later, I saw all this destruction.”

With communications down and media barred, it is impossible to independently verify assertions made by any side.

“Security forces are telling us that Mekelle is the prize needed to defeat the TPLF, and in the next 48 hours they will be carrying out attacks on different sites in the capital of the Tigray region. They are calling this a ‘law-enforcement operation’ against ‘impunity’ to bring it to an end once and for all,” he said.

In a statement, the government’s task force said federal forces had “liberated” the Raya, Chercher, Gugufto and Mehoni localities on the eastern front along with Shire on the western front of the conflict.

They had destroyed TPLF military bases in both areas and was now heading for the state capital Mekelle, the statement said. “The force of the junta is now retreating, and the army is marching to bring the TPLF junta to justice.”

Later on Tuesday, the task force accused the TPLF pf of destroying bridges connecting Mekelle with the rest of the country.

“Anxious about the advance [of central government forces], the junta has destroyed four bridges that lead to Mekelle,” said a statement, adding that there was also destruction in the key road between Shire and Axum.

There was no immediate comment by the TPLF. Tigray’s leaders have accused federal forces of knocking out a dam and a sugar factory as well as “mercilessly” attacking people in the region of more than 5 million. The government denies targeting civilians.

Meanwhile, the United Nations refugee agency warned on Tuesday that a “full-scale humanitarian crisis” was unfolding in Ethiopia.

Hundreds of people have been reported killed since the fighting began on November 4, after Abiy accused the TPLF of attacking a federal army base.

Both sides are accused of carrying out atrocities against civilians, while more than 27,000 people have fled the heavy fighting to seek refuge into neighbouring Sudan. Hungry, exhausted and scared refugees from the Tigray continue to arrive with terrifying accounts of the war.

“These people are coming with knives and sticks, wanting to attack citizens. And behind them is the Ethiopian army with tanks. The knives and the sticks aren’t the problem, it’s the tanks,” said one refugee, Thimon Abrah. “They struck and burned the entire place.”

“When a man, or even a child, is slaughtered, this is revenge,” said another, Tedey Benjamin. “This is a tribal war.”

Abiy has appealed for refugees to come home as his government promises the war will end quickly, though analysts fear a protracted conflict given the considerable military muscle on both sides.

With hundreds of thousands of Tigrayans dependent on food aid even before the conflict, suffering is worsening fast even as the UN and aid agency staff scale back for security reasons.

A convoy carrying about 200 passengers, mainly workers for international organisations, reached Ethiopia’s capital, Addis Ababa, late on Monday.

Another convoy of four buses and several cars, carrying about 400 foreigners from Mekelle, is expected to arrive in the capital on Wednesday, according to reports.

Over the weekend, Tigrayan forces fired rockets into the capital of neighbouring Eritrea, Asmara, escalating a conflict that threatens to destabilise the wider Horn of Africa region.

Federal forces claim to control Tigray’s western zone, where fighting has been heavy, and over the weekend said they seized the town of Alamata, south of Mekelle.

The UN, the African Union and various countries are pressing for talks, but Abiy is resisting, saying the government would only negotiate when it restored the rule of law in Tigray.

On Monday, Abiy sent his foreign minister to Uganda and Kenya to explain what the government describes as an internal conflict to leaders of those countries. Ethiopian officials said the visits do not mean negotiations are starting.

“A war in Ethiopia would give the entire continent a bad image,” Ugandan President Yoweri Museveni wrote on Twitter after the meeting. “There should be negotiations and the conflict stopped, lest it leads to unnecessary loss of lives and cripples the economy.”

The Nobel Committee, which awarded its prestigious peace prize to Abiy for his efforts to heal divisions with Eritrea, said late on Monday it was “deeply concerned” over the fighting.

The federal government has so far rejected international pleas for dialogue and de-escalation.

“The TPLF raided our Northern Command, it looted our artillery and it also surrounded our soldiers and taken hostage of them,” Zadig Abraha, the Ethiopian minister in charge of democratisation, told Al Jazeera on Tuesday. “What government would possibly negotiate [after all that]?” he asked.

The minister said “there are conditions that the TPLF has to meet”, including handing over the top leadership “that are involved in the perpetration of this crime”, among others.

The TPLF had objected to the postponement of national elections until next year because of the COVID-19 pandemic and considers Abiy’s federal government illegal, saying its mandate has expired.

Tigrayan leaders say 44-year-old Abiy – last year’s Nobel Peace Prize winner – has persecuted and purged them from government and security positions since taking office in 2018.

Tigrayan leader Debretsion Gebremichael told the AFP news agency on Tuesday “the government and people of Tigray” would hold their ground.

“This campaign cannot be finished. As long as the army of the invaders is in our land, the fight will continue. They cannot keep us silent by military force,” he said.

Tigrayan forces might seek to dig in as the military advances into the more mountainous terrain towards Mekelle, said Matt Bryden, the founder of Nairobi-based regional think tank Sahan.

“I would guess as they [the Ethiopian army] enter the highlands, heavier fighting is likely to start,” he said. (Al Jazeera)

Update news