An attack on an African Union peacekeeping base in the Somali capital Sunday killed 11 people and injured 15, the AU said, but it denied insurgent claims of a suicide attack. El Ghassim Wane, a spokesman for the AU in Addis Ababa, said the insurgents had fired mortars onto the base in Mogadishu. He gave no further details. But Sheik Muktar Robow, a spokesman for the al-Shabab insurgent group, insisted that "Our fighters have carried out two suicide attacks on the infidels in Mogadishu, inflicting heavy losses." The AU peacekeeping force in Mogadishu has had a restricted mandate to guard key government installations in the two years it has been here. It has not been involved in fighting Islamic militants in the capital, battles that have killed thousands of civilians over the past two years. But hardline groups still view the peacekeepers as an occupying force. Al-Shabab, an extremist Islamic group, has threatened to focus its attacks on AU troops now that Ethiopian troops have left Mogadishu after a two-year deployment.