Longtime foes Ethiopia and Eritrea could be headed towards war, officials in a restive Ethiopian region at the centre of the tensions have warned, risking another humanitarian disaster in the Horn of Africa.

Direct clashes between two of Africa's largest armies would signal the death blow for a historic rapprochement for which Ethiopia's Prime Minister Abiy Ahmed won the Nobel Peace Prize in 2019 and could draw in other regional powers, analysts said.

It would also likely create another crisis in a region where aid cuts have complicated efforts to assist millions affected by internal conflicts in Sudan, Somalia and Ethiopia.

"At any moment war between Ethiopia and Eritrea could break out," General Tsadkan Gebretensae, a vice president in the interim administration in Ethiopia's Tigray region, wrote in Africa-focused magazine the Africa Report on Monday.

A 2020-2022 civil war in Tigray between the Tigray People's Liberation Front (TPLF) and Ethiopia's central government killed hundreds of thousands of people.

Fears of a new conflict are linked to the TPLF's split last year into a faction that now administers Tigray with the blessing of Ethiopia's federal government and another that opposes it.

On Tuesday, the dissident faction, which Tsadkan accused of seeking an alliance with Eritrea, seized control of the northern town of Adigrat.

Getachew Reda, the head of Tigray's interim administration, in turn asked the government for support against the dissidents, who deny ties to Eritrea.

"There is clear antagonism between Ethiopia and Eritrea," Getachew told a news conference on Monday. "What concerns me is that the Tigray people may once again become victims of a war they don't believe in."

'DRY TINDER WAITING FOR A MATCH'

Ethiopia's federal government has not commented on the tensions. Eritrea's information minister dismissed Tsadkan's warnings as "war-mongering psychosis".

However, Eritrea ordered a nationwide military mobilisation in mid-February, according to UK-based Human Rights Concern - Eritrea.

And Ethiopia deployed troops toward the Eritrean border this month, two diplomatic sources and two Tigrayan officials told Reuters, asking not to be named due to the sensitivity of the situation.

Reuters could not independently verify these developments. Eritrean and Ethiopian government spokespeople did not respond to requests for comment.

Payton Knopf and Alexander Rondos, the former US and EU envoys to the region, say the prospects of a new war are real.

"The deterioration of the political and security situation in Tigray is dry tinder waiting for a match," they wrote in an essay for US publication Foreign Policy on Wednesday.

Relations between Ethiopia and Eritrea have long been fraught.

Eritrea broke away from Ethiopia in 1993 after a 30-year fight for independence. The neighbours then fought a 1998-2000 border war.

They remained formally at war until 2018, when Abiy and Eritrean President Isaias Afwerki agreed to normalise ties. Eritrean troops even supported Ethiopian federal forces against TPLF-led rebels during the Tigray civil war.

But the exclusion of Eritrea from subsequent peace negotiations once again chilled relations.

Eritrean officials have bristled at repeated public declarations by Abiy since 2023 that landlocked Ethiopia has a right to sea access, comments some analysts view as an implicit threat of military action against Eritrea, which lies on the Red Sea.

Last October, Eritrea, an authoritarian and insular state, signed a security pact with Egypt and Somalia that was widely seen as aimed at countering Ethiopia's potential expansionist ambitions.