President Abdel Fattah al-Sisi warned Sunday that “Egypt will not allow anyone to threaten Somalia,” after a controversial maritime deal between rival Ethiopia and the breakaway region of Somaliland.

During a joint press conference with Somali President Hassan Sheikh Mohamud in Cairo, Sisi reiterated Egypt’s rejection of the deal for sea access as a violation of Somalia’s sovereignty.

In a “message to Ethiopians”, Sisi warned against “anyone trying Egypt, and trying to threaten its brothers, especially if our brothers ask us to stand by them.”

Cairo and Addis Ababa have been at loggerheads for years, trading incendiary words over Ethiopia’s mega-dam project on the Blue Nile, which Egypt says threatens its fragile water security.

Egypt’s foreign minister last week called Addis Ababa “a source of instability in its region”.

Regional tensions have escalated since landlocked Ethiopia struck a memorandum of understanding (MoU) with Somaliland on January 1 that gives it much sought-after access to the sea.

Mogadishu has branded the maritime pact an act of “aggression” and on Thursday said there was “no space for mediation unless Ethiopia retracts its illegal MoU and reaffirms the sovereignty and territorial integrity of Somalia.”

Somaliland, a former British protectorate of 4.5 million people, has not had its independence claim recognised by the international community.

Mogadishu vehemently opposes Somaliland’s quest for statehood but the fragile central government exercises little authority over the northern region, which has its own government, security forces and currency.

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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.