“We will bury this enemy with our blood and bones and make the glory of Ethiopia high again,” said Abiy, who won the Nobel Prize for settling Ethiopia’s long-time conflict with Eritrea.

UN Secretary-General Antonio Guterres posted on Twitter that he spoke with Abiy on Wednesday “to offer my good offices to create the conditions for a dialogue so the fighting stops”.

An earlier call to “bury” the enemy contained in a statement posted on Abiy’s official Facebook page over the weekend was removed by the platform for violating its policies against inciting and supporting violence, the company said.

During Wednesday’s commemoration of the first anniversary of the conflict, a moment of silence was observed at the candlelit ceremony to commemorate those killed on November 3, 2020, when forces loyal to the Tigray People’s Liberation Front (TPLF) – including some soldiers – seized military bases in Tigray. In response, Abiy sent more troops to the northern region.

The TPLF led Ethiopia’s ruling coalition for nearly 30 years but lost control when Abiy took office in 2018 following years of anti-government protests.

Relations with the TPLF soured after they accused him of centralising power at the expense of Ethiopia’s regional states – an accusation Abiy denies.

The conflict in Africa’s second most populous country has killed thousands of people, forced more than two million from their homes, and left 400,000 people in Tigray facing famine.

A joint investigation by the United Nations and Ethiopia’s state-appointed human rights commission published on Wednesday found that all sides fighting in the war had committed violations that may amount to war crimes.

The African Union said on Wednesday that its chair, Moussa Faki Mahamat, was following the escalation in Ethiopia with deep concern. He urged the parties to engage in dialogue.

Ethiopia’s neighbour Kenya increased security along the border.

Will Davison, senior analyst at the International Crisis Group think-tank, said the Tigrayan forces’ gains had increased pressure on Abiy’s government.

“Right now, it looks difficult for the federal coalition to hold off the Tigray forces’ advance, and some of their leaders have recently said that at this late stage they are not looking to negotiate with Abiy,” he said.

The Tigrayan forces are now in the town of Kemise in Amhara state, 325km (200 miles) from the capital, TPLF spokesman Getachew Reda said on Wednesday, pledging to minimise casualties in their drive to take Addis Ababa.

“We don’t intend to shoot at civilians and we don’t want bloodshed. If possible we would like the process to be peaceful,” he said.

The United States embassy in Addis Ababa has authorised the voluntary departure of non-emergency government staff and family members. The step came after the US said it was “gravely concerned” about the escalating violence and expansion of hostilities, repeating a call for a halt to military operations and the beginning of ceasefire talks.

A regional analyst in touch with the parties to the war and who spoke on condition of anonymity said the TPLF was likely to hold off on any advance on Addis Ababa until they secured the highway running from neighbouring Djibouti to the capital.

That requires seizing the town of Mille. Getachew said on Tuesday that Tigrayan forces were closing in on Mille.

It also allows authorities to arbitrarily arrest anyone suspected of collaborating with “terrorist groups” with a court order and detain them while the state of emergency lasts.

The government designated the TPLF a terrorist group in May.