The United Nations on Friday urged Ethiopia and Eritrea to respect each other's territorial integrity, voicing concern over "renewed tensions" between the two neighbouring countries.

For months, the Horn of Africa nations have traded accusations of destabilisation, raising the spectre of a new war.

Eritrea, which gained independence from Ethiopia in 1993 after a long armed struggle, accuses its landlocked neighbour of eyeing its Assab port.

Ethiopian authorities, meanwhile, say Eritrea is "actively preparing for war" and funding armed groups fighting federal forces.

UN chief Antonio Guterres urged both sides to "recommit to the vision of lasting peace and the respect for sovereignty and territorial integrity" under the Algiers Agreement, which ended a border war that killed tens of thousands between 1998 and 2000, his spokesman Stephane Dujarric said in a statement.

The two countries have had strained relations since then, with fighting flaring up again in Ethiopia's war-scarred Tigray region.