Islamist rebels attacked Ugandan peacekeepers and briefly entered their Mogadishu base on Saturday, but a spokesman for the African Union force said it suffered no casualties.
The overnight raid, which set off a 90-minute battle, took place two days after a fugitive Islamist commander, who is believed to be linked to al-Qaida, ordered his fighters to target the Ugandans and kill their officers.
"We killed one insurgent. His body is still lying there," A.U. spokesman Paddy Ankunda told Reuters.
"There are no casualties on our side. They attacked us in two groups using machine guns and rocket-propelled grenades and we defended ourselves. We have a mandate to defend ourselves," he said.
The attack took place as a local non-governmental organization said nearly 470 civilians had been killed in fighting between pro-government forces and insurgents in Mogadishu since October.
About 1,600 Ugandan soldiers have been in the city since March to support a fragile interim government backed by the West, the United Nations and regional power Ethiopia.
Somalia faces Iraq-style insurgency
The local authorities and their Ethiopian military allies have faced an Iraq-style insurgency of roadside bombings and political killings since the start of the year when they drove a hardline Sharia courts group out of the capital.
Hundreds of thousands have fled the fighting this year, and the attacks have increasingly targeted the peacekeepers — the vanguard of a long-awaited 8,000-strong AU force.
Showing increasing boldness, some rebels infiltrated the Ugandan base at the strategic K4 junction in the latest attack.
"They shared the buildings we occupy. I don't know how they did that," Ankunda said. "The fighting lasted an hour and a half. But we can't be intimidated and won't withdraw. We're here to assist the Somali people and we shall continue doing so."
High death tolls
Speaking to Reuters on Saturday, the chairman of the Elman Peace and Human Rights Organization said 469 civilians had been killed by fighting in Mogadishu since the start of October.
Sudani Ali Ahmed said 155 residents were killed and 281 wounded last month, while 314 had been killed so far in November and 559 wounded as Ethiopian troops sought to crush the rebels.
"We condemn the international community for watching the cruelty in Somalia like a film and not bothering to help," Ahmed said. "What is going on Somalia is a war crime."
In more bloodshed on Saturday, a bus packed with passengers struck a landmine in the south of the city. Local media said two people were killed and at least 15 wounded, five seriously.
Thursday's comments by Islamist commander Aden Hashi Ayro were clearly meant to boost the insurgency.
Ayro, in hiding since the Islamists were routed in January, accused Ethiopia and Uganda of invading and said all other African troops sent to Somalia would face holy war.
Ayro, who security sources say was trained in Afghanistan in the 1990s, vowed to take his fight to Ethiopia's capital.
"They beheaded our children, women and elderly people in Mogadishu and we must behead theirs in Addis Ababa," he said in the 20-minute recording posted on Somali Web sites.