A humanitarian source in Afar told AFP news agency on Thursday that Tigrayan forces had launched heavy artillery attacks as they attempted to take control of the town of Yallo, near the border with Tigray.

“We are in the situation of full-blown war now,” TPLF vice-president Amanuel Assefa is quoted by the news agency as saying.

The latest escalation follows months of rising tensions between Prime Minister Abiy Ahmed’s government and Tigray authorities, who fought a devastating war from 2020 to 2022.

That ended in an African Union-brokered peace deal but over recent months both sides have been accusing each other of violating the agreement.

It was one of the most deadly conflicts this century – the AU’s mediator estimated some 600,000 people died as the fighting drove the region to the precipice of famine.

On Sunday, the TPLF announced an alliance with six other armed groups to oust the government.

Following the seizure of the airports, Ethiopian Airlines has cancelled all flights to Tigray.

Residents of Tigray’s main city of Mekelle told the BBC that local forces had taken over control of the city’s airport from the national police early on Wednesday.

This followed reports of drone strikes in Tigray in recent days.

A Mekelle resident told the BBC’s Newsday programme on Thursday there had been no clashes in the city, unlike in the previous war, with most fighting happening elsewhere.