The video also shows alleged Shabaab attacks in which Kenyan uniformed personnel are killed and weapons, equipment and identity documents captured.

The captive asks Kenyan President Uhuru Kenyatta not to forget other nationals captured by Shabaab militants. The clip ends with the soldier being shot three times in the head from behind by an unidentified militant.

Uganda, Kenya, Burundi, Djibouti and Ethiopia all contribute troops to the 22,000-strong AU Mission in Somalia (AMISOM) which is fighting the Shabaab and defending the internationally-backed government in Mogadishu.

Shabaab has made repeated calls for foreign troops to leave Somalia.