Ethiopia's army chief made the accusation as fighting intensified with Tigrayan forces and rebels reportedly seized an Afar town.
A report from Deutsche Welle — English sets out the main available details, with claims kept attributed to their sources.
The army chief has accused Eritrea of funding and supporting armed groups in an effort to weaken Ethiopia, as fears grow of a new civil war.
Analysts say Eritrea's strategic importance is rising after Washington lifted key sanctions, even as Houthi attacks disrupt Red Sea shipping and violence resumes in Ethiopia's Tigray region.
Washington has removed sanctions imposed on Eritrea's ruling party and military during the Biden administration over the Tigray conflict, saying the move serves US strategic goals in the Red Sea region.
Relatives of senior Eritrean politicians detained without trial say they still do not know whether their parents are alive, according to a BBC News report.
More than 180 authors, including Olga Tokarczuk and JM Coetzee, have signed a letter to Eritrea's president marking 25 years since 12 writers were detained without trial