At least nine people have been killed and 53 others wounded in renewed fighting in Somalia's capital.

Local officials in Mogadishu said the fighting took place between pro-government troops and members of Somalia's al-Shabab group at a camp for the displaced.

The clashes erupted late on Monday when al-Shabab fighters attacked government positions to the south of the capital, sparking a heavy exchange of artillery fire between the fighters and government troops backed by African Union forces.

"Our teams picked up nine civilians killed in the fighting and 53 wounded," Ali Muse Mohamud, the head of the Mogadishu ambulance service, told the AFP news agency.

"There are a lot of casualties because the fighting started without any warning while people were preparing to break their Ramadan fast," he said.

The majority of the dead and wounded lived in a camp for displaced people in the south of the city, far from the districts that normally see fighting. Most were hit by mortar fire on the camp.

"Four of the dead, including three children, belonged to one family that had settled in the camp. One mortar bomb alone killed seven people," Duniya Mohamed, a witness to the attack, said.

Wracked by conflict

Al-Shabab, which has been accused of links to al-Qaeda, controls most of southern Somalia.

The group has been engaged in fierce fighting with the current 6000-strong AU force in Somalia, but the AU force has been restricted to retaliatory fire by the mandate it has been operating under.

Human rights groups warn that if the troops are allowed to expand their operations, civilians in Somalia will be further exposed to violence.

Somalia has been wracked by conflict for decades, with the latest bout of fighting erupting after Ethiopian troops, operating with US approval, invaded and overthrew the Union of Islamic Courts, whose rule had brought a period of relative stability to the troubled country.