The African Union (AU) Transition Mission in Somalia (ATMIS) vowed on Saturday to partner with local security forces to pursue peace despite increased attacks by al-Shabab in the country.

ATMIS also condemned the brazen attack on a commercial convoy by the militant group on Friday night which resulted in the death of 20 people and the destruction of seven trucks carrying urgently needed food and water supplies in the central Somali town of Hiran.

"ATMIS commiserates with the families of those killed and remains committed to working with Somali security forces towards peace and security in Somalia," the AU mission said in a statement issued in Mogadishu, the capital of Somalia.

The statement came as Hiran regional security officials confirmed that the death toll from the terrorist attack rose to 20 while seven trucks carrying food supplies from Beledweyne to Mahas in HirShabelle State were burnt.

The regional security officials also said two vehicles ferrying rescuers were targeted with improvised explosive devices by al-Shabab terrorists in the latest attack which has also been condemned by the Somali government.

Residents said the latest assault was a retaliatory attack carried out by al-Shabab on a local militia dubbed, Ma'awisley which is backed by the Somali National Army (SNA) that has been fighting al-Shabab militants recently in a bid to push them out of the Hiran region.

The Somali National Army (SNA) backed by the AU Mission in Somalia drove al-Shabab out of Mogadishu in 2011, but the terror group is still capable of conducting attacks, targeting government installations, hotels, restaurants and public places.