At least 20 civilians have been killed and dozens more injured in clashes between Somali government troops and opposition forces in the capital Mogadishu.

The latest round of fighting began on Friday and follows a lull of about two weeks.

Yusuf Mohamed Siad, the Somali deputy defence minister, said on Saturday, that government forces had killed a number of rebel fighters, including "three of their commanders".

"Al-Shabab and their ally, Hisbul Islam, attacked our military positions. They gained nothing, but they suffered casualties," Siad said.

"We have killed many of them including three of their commanders. For our part we have received no casualties and you can see we [are] still manning our large part in which we have taken over the insurgents."

Children 'killed'

His comments come after witnesses and medical workers said overnight fighting in several parts of the capital left at least 11 people dead and another 62 injured, some of those wounded have since died from their injuries.

"We received around 62 civilians who were injured during Friday clashes and nine of them died at the hospital," Mohamed Ali, a doctor at Mogadishu's Madina hospital, said.

"Most of the victims are children who were seriously injured by mortar shrapnel."

Since taking control of much of Mogadishu after bloody clashes last year, the al-Shabab fighters have repeatedly carried out many attacks against foreign peacekeepers and the government troops, inflicting heavy casualties.

Civilians have borne the worst brunt of the relentless fighting, many of them caught in crossfire or killed by mortar shells fired in retaliation to attacks by the opposition who operate in residential areas.

Al-Shabab, who control 80 per cent of south and central Somalia, vowed to topple the internationally-backed government, which owes its survival to the African Union (AU)forces.

Somalia has been wracked by two decades of bloody violence sparked by the ouster of President Mohamed Siad Barre.

As a result, the horn of Africa nation has not had a stable government since 1991, and fighting between the rebels and government troops has escalated the humanitarian crisis in the famine-ravaged country.