Somaliland, a former British protectorate, declared independence from Somalia in 1991 but the move has not been recognised internationally.
Ethiopia, the second most populous country in Africa, was cut off from the coast after Eritrea seceded and declared independence in 1993.
Ethiopia said it held talks Monday on military cooperation with Somaliland, just a week after a deal with the breakaway Somali region on sea access stoked tensions in the Horn of Africa.
The discussions in Addis Ababa were held the same day Somalia's President Hassan Sheikh Mohamud began a visit to neighbouring Eritrea.
Somalia is seeking international support over the controversial January 1 agreement between Ethiopia and Somaliland -- a separatist region over which Mogadishu exercises little real authority.
The central government has branded the memorandum of understanding (MoU), which gives landlocked Ethiopia access to the Red Sea via Somaliland, an act of "aggression" and a violation of its sovereignty.
Despite regional and international concern over the pact, Ethiopia's army chief Birhanu Jula "discussed military cooperation" with his Somaliland counterpart Nuh Ismail Tani on Monday, according to a statement on Facebook posted by Ethiopia's defence force.
Meanwhile, Mohamud's arrival in Asmara was announced by his office and the Eritrean information ministry in separate posts on X, accompanied by pictures of him being welcomed by Eritrean President Isaias Afwerki.Â
"The two leaders will discuss issues of mutual benefit for both nations including strengthening ties & fostering cooperation," Mohamud's office said.
Dubbed the "North Korea" of Africa, Eritrea -- which has been ruled with an iron fist by Isaias since independence -- is one of the world's most isolated states.
The African Union and the United States among others have called for calm and respect for Somalia's sovereignty and territorial integrity.
Somaliland, a former British protectorate, declared independence from Somalia in 1991 but the move has not been recognised internationally and is staunchly opposed by the central government in Mogadishu.
Ethiopia has long sought coastal access and in October last year Prime Minister Abiy Ahmed alarmed its neighbours when he said the country's existence was tied to the Red Sea.
The remarks came against a backdrop of apparent tensions with Eritrea, which had allied with Ethiopian government forces in the two-year Tigray war that ended in November 2022.
Abiy later said Ethiopia would not invade any neighbouring country, while insisting his government would not abandon its demand for port access.
The January 1 pact gives Ethiopia access to commercial maritime services and a military base, with Somaliland leasing it 20 kilometres (12 miles) of coastline for 50 years.
The January 1 pact gives Ethiopia access to commercial maritime services and a military base, with Somaliland leasing it 20 kilometres (12 miles) of coastline for 50 years.
Ethiopia, the second most populous country in Africa and one of the biggest landlocked nations in the world, was cut off from the coast after Eritrea seceded and declared independence in 1993 following a three-decade war.
Also Monday, Djibouti said it was following "with great concern" the tensions between Somalia and Ethiopia and called for dialogue between the two nations to de-escalate the situation.
Djibouti, currently head of the regional grouping IGAD, said it was pursuing efforts with member states to resolve the crisis.
Just days before the Ethiopia deal, Djibouti had hosted talks that saw Somalia and Somaliland agree to resume dialogue after years of stalemate.