The 12-day conflict between Ethiopia’s government and forces in the country’s Tigray region has escalated.
The Tigrayan forces fired rockets across the border into neighbouring Eritrea, after claiming Ethiopian soldiers were using an Eritrean airport to attack Tigray.
Ethiopia’s prime minister appeared to deny the accusations in a tweet.
But analysts say the latest attacks mark a major uptick in a conflict which has displaced thousands of civilians.
Ethiopia has been through big changes since Prime Minister Abiy Ahmed came to power in 2018. He was awarded the Nobel peace prize last year after reaching out to make peace with neighbouring Eritrea, with whom Ethiopia had fought a bloody war two decades ago.
But the widespread reforms he pushed through sidelined the Tigrayans of the Tigray People’s Liberation Front party (TPLF) who had long dominated the political scene – and in recent weeks, tensions between the party and the federal government seriously escalated.
Animosity between the government in Tigray and Eritrea goes back a long way, according to the BBC’s Africa regional editor Will Ross, who says much of it stems from that border war of 20 years ago which left tens of thousands of soldiers dead.
On Sunday, the Ethiopian Human Rights Commission said gunmen had killed at least 34 people on a passenger bus on Saturday night in the western region of Benishangul-Gumuz.
The region has seen other acts of violence recently and there has so far been no known link with the Tigray region.
What happened in the attack on Eritrea?
On Saturday night, residents of Asmara – Eritrea’s capital – reported hearing loud explosions, amid reports of rockets landing near the city’s airport. No casualties have been reported yet.
Tigrayan leader Debretsion Gebremichael has suggested that his forces have been fighting 16 divisions of the Eritrean army on several fronts for the past few days.
The Tigrayans have also accused Eritrean forces of crossing into Ethiopia to back federal forces there.
On Sunday, in a tweet, Mr Abiy appeared to deny that Ethiopian national forces were working with Eritreans, saying that Ethiopia was “more than capable of attaining the objectives of the operation by itself”.
But while Eritrea and Ethiopia have denied co-operating in the conflict, our regional editor says reports of fighting along the border, and of Ethiopian soldiers being treated in Eritrean hospitals, suggest the opposite is true.
Analysis: Two men with a common enemy
By Will Ross, BBC Africa regional editor
With missiles being fired into Eritrea this conflict has now become far more serious and is likely to be harder to stop. The repercussions could now cause instability in the whole region.
But many people familiar with recent political developments had predicted trouble was brewing when Ethiopia’s Prime Minister Abiy Ahmed became a strong ally of Eritrea’s authoritarian leader, Isaias Afwerki.
Now the two men have a common enemy – the Tigrayan politicians of the TPLF who dominated Ethiopia’s political scene for years, including the time when Ethiopia and Eritrea fought a border war that left tens of thousands dead.
International calls for dialogue have so far been ignored and thousands of civilian refugees continue to flee the fighting into Sudan.