Militant group al-Shabab has promised to retaliate for the execution of 13 suspected Islamist fighters by authorities in Somalia's Puntland region.
In an audio recording posted online, al-Shabab spokesman Sheikh Ali Mohamud Rage said the 13 were "innocent Muslims." He said the group will issue "tough punishment" to all those involved in their arrest, conviction and execution.
The 12 men and one woman were killed by firing squad, in secret, outside the town of Bosaso on Tuesday.
A local official told VOA they had been convicted of killing a local religious scholar, regional lawmakers and security officials.
Somali, Ethiopian and African Union forces have pushed al-Shabab out of Somalia's major towns and cities but the al-Qaida-linked militant group remains active.
The group claimed responsibility for an attack in Mogadishu last month that killed more than 30 people.
Some of the group's fighters have infiltrated the semi-autonomous Puntland region following al-Shabab's setbacks in southern Somalia.