Ethiopia's foreign minister has accused neighbouring Eritrea of military aggression and of supporting armed groups inside Ethiopian territory, according to a letter seen by Reuters and verified by the foreign ministry.
The two longstanding foes who waged war against each other between 1998 and 2000, signed a peace deal in 2018 and were allies during Ethiopia's two-year war against regional authorities in the northern Tigray region.
But Eritrea was not a party to the 2022 agreement that ended the Tigray conflict, and relations between the two nations have plunged into acrimony since then.
Recent clashes between Tigrayan forces and Ethiopian troops have raised fears of a return to war.
An Eritrean government spokesperson said officials were checking whether the letter had been delivered to the foreign ministry.
The February 7 letter from Ethiopia's Foreign Minister Gedion Timothewos to his Eritrean counterpart, Osman Saleh, said Eritrean forces had occupied Ethiopian territory along parts of their shared border for an extended period and had provided material support to militant groups operating inside Ethiopia.
"The incursion of Eritrean troops further into Ethiopian territory...are not just provocations but acts of outright aggression," the letter said, calling for the immediate withdrawal of Eritrean forces and an end to all cooperation with armed groups.
Gedion said recent developments pointed to "further escalation," citing joint military manoeuvres between Eritrean forces and Ethiopian armed groups near the northwestern border.
Eritrea has bristled at repeated public declarations by Prime Minister Abiy Ahmed that landlocked Ethiopia has a right to sea access - comments many in Eritrea, which lies on the Red Sea, view as an implicit threat of military action.
In his letter, Gedion said Ethiopia remained open to dialogue if Eritrea respected its territorial integrity. He said Addis Ababa was willing to engage in good-faith negotiations on all matters of mutual interest, including maritime affairs and access to the Red Sea through the Eritrean port of Assab.
(Reporting by Dawit Endeshaw in Addis Ababa and Giulia Paravicini in Nairobi; Editing by Ros Russell)
