More than 20 killed in Mogadishu weekend fighting

The African Union mission in Somalia (AMISOM) said the fighting was triggered by its discovery of a mile-long trench system used by the Al Qaeda-inspired Shebab insurgents in the capital.

The force said in a statement the Shebab were "using the trench and tunnel system to infiltrate fighters closer to AMISOM positions without detection. It also acted as a protected logistic resupply and casualty evacuation route."

The Shebab "counter-attacked in a desperate attempt to recover this vital asset," AMISOM said in a statement, triggering two days of intense clashes pitting rebels against Somali soldiers backed by AMISOM.

Both sides claimed victory in the fighting, which kicked off before dawn on Saturday and claimed its customary toll on civilians, killing at least 15 of them over two days.

Ali Muse, who heads Mogadishu