Ethiopia has accused Eritrea of an "all-out invasion" of its northern Tigray region and warned it will defend itself, days after residents reported that Eritrean troops had crossed into the country.
In a letter dated 8 October to UN Security Council members, Ethiopia's Foreign Minister Gedion Timothewos called the incursion a "blatant act of aggression that engages Ethiopia's inherent right to self-defence." He said Eritrean forces had advanced up to 60 kilometres (37 miles) into Tigray.
The letter read: "In this time of difficulty, when Ethiopia is left with no other option but to defend itself, we count on your understanding, support, and solidarity."
Eritrea rejected the accusations. Information Minister Yemane Gebremeskel said his country was facing "an unprovoked war of aggression" from its neighbour. He accused Ethiopia of "duplicity in their most extreme forms" and said Addis Ababa was "openly working to bring about regime change in Eritrea by providing shelter and support to certain mercenaries who claim to be opposition."
Ethiopian drone strikes reportedly targeted Eritrean forces in the Tigrayan town of Adigrat on Wednesday and Thursday, amid fears of a wider regional conflict.
US-based conflict monitor ACLED said "Eritrean troops and ammunition" in Adigrat were hit by "multiple drone strikes" overnight. One resident told sources that "there were many, many drone strikes" and that some Eritrean lorries had been destroyed. Another witness said Eritrean forces appeared to be retreating north following the strikes.
The current fighting broke out two weeks ago between the Ethiopian government and the Tigray People's Liberation Front (TPLF), the party that controls the Tigray region. Both sides blame each other for violating a 2022 peace deal that ended a two-year civil war.
Ethiopia accuses Eritrea of backing the TPLF, which Eritrea denies. Eritrea, in turn, accuses Ethiopia's leaders of seeking a pretext to seize Eritrean territory.
During the civil war, Eritrea was a key ally of the Ethiopian government and fought alongside it against the TPLF. Relations between the two countries have since deteriorated sharply, largely over Ethiopian Prime Minister Abiy Ahmed's ambition to gain access to one of Eritrea's Red Sea ports. Diplomatic ties were severed last week.
Eritrea gained independence from Ethiopia in 1993. Relations were only normalised in 2018, when Abiy Ahmed came to power.
The latest unrest follows months of tension and the formation in September of a new alliance of armed groups in Ethiopia, which includes the TPLF. Last week, TPLF forces withdrew from Tigray's main city of Mekelle, located 115 kilometres (71 miles) south of Adigrat, which is now under Ethiopian army control.
