Raid follows an attack in January by al-Shabaab on a base used by Kenyan soldiers in which the Islamists claimed dozens of troops were killed
AMISOM mission confirms attack--if death toll holds would be among the worst attacks on the AU force.
Thanked Burundi, Djibouti, Ethiopia, Kenya and Uganda which contribute troops to the African Union stabilisation mission in Somalia.
Shabaab gets more deadly as bomb blast on UN bus kills 10. Claims deaths of Burundi and Kenyan African Union troops
Puntland had escaped militant violence until recently. Shabaab says it targeted the UN because its "part of the colonisation force in Somalia".