The African Union mission in Somalia (Amisom) has denied it supported government troops in recent clashes with the Ahlu Sunna wal Jama'a Sufi militia in the central town of Guriel.
In a statement, Amisom said the allegations were "false, toxic and malicious".
They were "deliberately intended to cause disaffection between Amisom and Somali communities", the mission said.
Ahlu Sunna had accused Amisom of siding with the Somali national army in the battle for the control of Guriel, in which at least 120 people were killed.