According to a local media report, at least three Ugandan soldiers have been injured in an attack on African Union troops in Somalia's capital where the 1,600 peacekeepers are based.
AU spokesman Paddy Ankunda told the BBC that soldiers were guarding Mogadishu's port when mortars were fired at them.
He called for more peacekeepers to enable them to take over positions under the command of Ethiopian troops.
Somalia has seen a surge in violence since Ethiopian-backed government troops ousted Islamists last December.
Some 1,600 Ugandan troops are in Mogadishu as part of a planned 8,000-strong AU force to support the interim government.
Capt Ankunda said this was the fourth attack on the AU troops since their deployment in March this year.
He also added that it was frustrating that the people they were protecting were attacking them.
"We are not demoralised by the attacks and we are still here to ensure that we achieve our mission," he told the BBC's Network Africa programme.
But he called for the international community to mobilise more peacekeepers so they could take over military positions from the Ethiopians.
Insurgent groups and Islamist remnants in Mogadishu are opposed to the presence of Ethiopian troops who they view as an occupying force.
At the moment Uganda troops are in charge of security at Mogadishu's air and sea port, presidential palace and strategic junctions within the capital.
Somalia has been without an effective government since the civil war began in 1991.
The UN says some 400,000 people have fled the violence in Mogadishu in the past four months.