Rival Somali regions have sent troops into disputed flashpoint zones in the north of the war-torn nation, Britain, the European Union and the United States said Saturday in a joint appeal for calm.
Troops from self-declared Somaliland in the northwest and soldiers from autonomous Puntland in the northeast have moved into contested areas of the northern Sool and Sanaag regions.
Somaliland and Puntland claim several areas in border zones including potentially valuable oil blocks, with both sides in certain cases issuing overlapping exploration licences.
"We call for the immediate withdrawal of armed forces from the disputed areas of Sool and Sanaag regions, and call on all actors to refrain from violence," read the statement from British ambassador Neil Wigan, EU envoy Michele Cervone d'Urso and US envoy James McAnulty.
Rival forces have clashed repeatedly in the region before, a lawless area bordering Ethiopia that does not recognise the authority of the weak central government based far to the south in Mogadishu.
"We urge restraint and oppose the use of force," the joint statement added.
Somaliland, a former British colony, broke away from Somalia in 1991, the year the rest of the Horn of Africa nation erupted into all-out civil war.
Puntland set up its own government in 1998, but unlike neighbouring Somaliland, it has not declared full independence.