Tension is brewing between Somalia and Ethiopia over the latter's controversial deal with breakaway Somaliland granting Addis Ababa access to the Red Sea port of Berbera and a leased military base.

Somalia on Tuesday vowed to defend its territory as it branded the accord an "aggression" while the European Union on Tuesday insisted the federal republic's sovereignty should be respected.

"This is key for the peace and stability of the entire Horn of Africa region," the statement from an EU spokesperson said.

The government in Mogadishu also said it had recalled its ambassador to Ethiopia and issued an appeal to the international community to stand by its side over the "blatant assault" on its sovereignty.

Somaliland, a former British protectorate of about 4.5 million people, has been seeking full statehood since claiming independence from Somalia in 1991.

But the move has not been recognized internationally and is fiercely opposed by Mogadishu although in reality the central government exercises little authority over the region's affairs.