The U.N.-backed Transitional Federal Government of President Sheikh Sharif Ahmed controls part of the capital, and AMISON — AU troops from Uganda and Burundi — is fighting to stop two hardline Islamist insurgent groups from taking over the rest.
The groups also control much of south and central Somalia.
“We have deployed 1,000 extra Burundian troops to Mogadishu two days ago,” Lieutenant Colonel Jastace Ciza told Reuters by phone from Bujumbura. “We have sent them to strengthen our forces in Mogadishu.”
Previously AMISOM soldiers numbered about 8,000.
Late last month insurgents killed six Burundian peacekeepers as the troops provided support to Somali government soldiers who had seized three militant bases in the capital.
The transitional government is viewed by the international community as the best hope of returning the Horn of Africa country to stability after two decades of conflict.
It has been facing a four-year insurgency led by the al Shabaab rebel group which professes loyalty to al Qaeda.
Separately Kenya which has been training Somali troops, has almost completed their deployment, with the last batch of some 600 soldiers about to be sent across the border, military sources in Mandera in the north east of the country said.