MOGADISHU, Somalia (AP) -- Mortars and missiles pounded parts of the Somali capital on Monday, killing at least 13 civilians in two separate battles between Islamic militiamen and the African Union peacekeeping force, witnesses and officials said.
In the first battle, heavily armed Islamist insurgents attacked a Burundian contingent of the AU force based at a former military academy in southwestern Mogadishu. Witnesses said eight civilians were killed.
Somali government spokesman Shiek Abdirisaq Qeylow confirmed the battle took place but did not give any other details. AU peacekeeping force spokesman Barigye Bahoku also confirmed the fighting.
Later Monday, residents reported missiles pounding Mogadishu's main market and said they were fired from an AU base nearby. Witnesses say they saw at least five civilians killed.
However, Bahoku said AU soldiers did not target the market in the city's south and instead were firing to protect a cargo ship docking at the port, which was being attacked by Islamic insurgents.
The African Union force, which is meant to protect key government installations such as the main air and sea ports, has become the main target of Islamic militias keen to overthrow the fragile U.N.-backed government. A loose alliance of Islamic groups opposed to the government control most of Mogadishu and other areas of southern Somalia.
Somalia has not had an effective government since 1991 when warlords overthrew dictator Mohamed Siad Barre and then turned on each other. The country has since descended into chaos and anarchy, and since last year has become a piracy haven.
Earlier on Monday, a firing squad of 10 al-Shabab men killed two Somalis in Mogadishu's main livestock market after the group accused them of being spies for foreign organizations.
Al-Shabab's Mogadishu chief Ali Mohamed Hussein says the group carried out the executions after determining that the two men worked for the AU force in Somalia and the U.S. Central Intelligence Agency.
The group's members vow allegiance to al-Qaida and it has foreign fighters in its ranks, raising fears al-Qaida is seeking to make a base in Somalia. Al-Shabab has carried out several whippings, amputations and executions to enforce its own strict interpretation of Islam.