Four African Union soldiers have been killed after a roadside bomb struck their convoy while on patrol at the north of Somalia's capital, Mogadishu.
The convoy was on patrol in the north of Mogadishu
AU spokesman Paddy Ankunda said five other soldiers were injured in the explosion targeted at the peacekeepers.
The attack is the deadliest on the peacekeepers since 1,600 Uganda soldiers deployed to the city in March.
A proposed force of 8,000 AU soldiers is due to take over security duties from the Ethiopian army.
Ethiopia's troops have been in Mogadishu since December at the invitation of Somalia's transitional government fighting Islamist insurgents and clan militiamen.
The attack comes only a day after Somalia's President Abdullahi Yusuf held talks with his Ugandan counterpart Yoweri Museveni in Kampala over the mission.
"We lost four and five were wounded. It was a roadside bomb and its intention was to hit the peacekeepers," Mr Ankunda told Reuters news agency.
He told the BBC that the wounded would be evacuated to Uganda for treatment.
The interim President's spokesman Hussein Mohamed Mohamud blamed the attack on Al-Qaeda elements still residing in Mogadishu and said they were hunting for them.
Earlier, four people were killed in the Gedo region, south of the capital, Mogadishu, when an unknown man threw an explosive at a cinema hall.
Baardheere Police chief Mohammed Yare said 20 others were seriously injured during the attack which took place while they were watching an Indian film.
"We do not know who is responsible for the attack but are investigating," Mr Yare told the Associated Press news agency.
On Monday, a similar blast occurred at a different cinema hall but there were no casualties during the incident.
Health officials in Gedo are battling to treat the victims of the attack and lack resources.
"Most have serious wounds and we are trying to help though we do not have enough medicine," Dr Bashir Ali of Shifo Hospital where most of the casualties were taken said. During the six-month rule in Mogadishu and southern parts of Somalia, the Union of Islamic Courts banned cinemas, television viewing and music.
No group has claimed responsibility for the attack.
On Tuesday, the US and the AU warned Ethiopia not to withdraw its troops from Somalia before peacekeepers are deployed to replace them.
AU commission chief Alpha Oumar Konare said it would be a "catastrophe" if Ethiopia pulled out too soon.
US Africa envoy Jendayi Frazer said it would probably be several months before the full peacekeeping force arrived.
Ethiopia's prime minister says he wants to withdraw all his troops, after they helped oust the Union of Islamic Courts.
Somalia has been without an effective national government for 16 years, controlled by rival militias and awash with guns.
Two foreign aid workers kidnapped last week in northern Somalia have been released.
Reports from the semi-autonomous region of Puntland say the pair - one Kenyan and one British - were being flown to Nairobi after their kidnappers handed them over to local elders.
Both men are employees of the London-based charity, Care International.
Its director in Somalia, David Gilmour, said they were relieved that the issue was resolved with nobody being harmed.
One of the kidnappers told Reuters news agency by satellite telephone that they had released the aid workers following successful negotiations with the Puntland authorities; but he did not elaborate.