“AMISOM is aware of the allegations levelled against its troops,” the force said in a statement.
A joint AMISOM and Somali army team has been set up “to investigate the matter and appropriate action will be taken once the facts of the case have been established,” the statement added.
The AU mission “strongly condemns any incidents of alleged sexual abuse or exploitation”, it said.
AU troops, including soldiers from five nations — Burundi, Djibouti, Kenya, Sierra Leone and Uganda — have been fighting against Al-Qaeda-linked Shebab insurgents in Somalia since 2007.
If confirmed, the case — which has been widely reported in recent days by media in Mogadishu — will badly dent the reputation of the AU force, and play into the hands of the Shebab.
Somalia’s army, an often rag-tag force incorporating militia fighters, has been in the past accused by rights groups of a string of abuses against women, including rape.
Still, the extreme nature of the woman’s allegations and the accusations of AMISOM involvement has shocked many.