The deputy mayor of Somali capital Mogadishu has accused African Union peacekeepers of opening fire on commuter buses, killing more than 20 civilians, reported dpa.
Abdifatah Shaweye said the peacekeepers opened fire indiscriminately on Monday after they were targeted by a roadside bomb.
"I saw more than 20 dead bodies, all of them civilians who were riding on four passenger buses at the time of the explosion," Radio Garowe reported Shaweye as saying.
Major Bahoku Barigye, a spokesman for the AU mission in Somalia (AMISOM), confirmed the bomb attack but denied his troops had targeted civilians in response.
The incident came just a few days after moderate Islamist Sheikh Sharif Sheikh Ahmed was sworn in as Somalia's new president.
Observers believe Sheikh Sharif is the best candidate to end the conflict in the Horn of Africa nation, which has been plagued by chaos since the 1991 ouster of former dictator Mohamed Siad Barre.
However, the main insurgent group al-Shabaab, which controls much of southern and central Somalia, said Monday it would continue fighting.
Sheikh Sharif is the head of the moderate branch of the Alliance for the Re-Liberation of Somalia (ARS) and headed up the Islamic Courts' Union (ICU) when it controlled Mogadishu for six months in 2006.
The ICU installed strict Islamic law and helped bring stability to Somalia during its reign, tackling warlords and curbing the piracy that once again exploded after it was ousted.
Ethiopian forces invaded in late 2006 to help kick out the ICU, sparking a bloody insurgency that has killed an estimated 16,000 civilians and displaced around 1 million.
With the departure of Ethiopia, only the undermanned AMISOM force of around 3,000 troops from Uganda and Burundi remains to back government forces.
The insurgency, combined with drought and rising food prices, has created a humanitarian catastrophe. About 3.25 million people in Somalia, almost half the population, are dependent on food aid.