Up to 40 people were killed and nearly a hundred more were wounded as an exchange of heavy shelling which began overnight continued in residential areas in the Somali capital of Mogadishu, a health official and witnesses said Friday.

The Somali government forces backed by the African Union peacekeepers in Mogadishu traded intense artillery shelling with Islamist insurgents who attacked government positions in the coastal city.

Witnesses said most of the shells landed in populated areas in the south of Mogadishu, causing huge casualties among civilians in the southern districts of Hawlwadag, Hodan and Wardigley.

"Overnight we ferried 39 wounded civilians and this morning ( Friday) we have so far taken 29 others to the health centers around Mogadishu. We are primarily concerned about helping wounded people but our staff reported seeing almost 30 dead people," Ali Muse, an official with a voluntary ambulance service in Mogadishu told Xinhua.

The official said he expected the causality figures to rise as the fighting and shelling continued in several parts of the capital between allied Islamist insurgent groups of Al-Shabaab and Hezbul Islam and the Somali government forces backed by African Union peacekeepers.

Another ambulance service in Mogadishu reported that its vehicles took nearly thirty more injured civilians while its staff said they saw almost ten dead people since the start of the shelling late on Thursday night.

Witnesses said many of the wounded were trapped in their homes as the shelling hits civilian homes in south Mogadishu where the sound of the heavy artillery could be heard.

So far neither the Somali government nor the AU peacekeepers or the insurgent groups commented on the latest flare-up of fighting in Mogadishu.

Insurgent fighters have on Thursday claimed gaining grounds from the government forces after capturing the key central Somali town of Beledweyn in Hiran province, as well as two other towns in southern Gedo region which were briefly taken by pro-government forces this week.

Insurgent groups control much of south and center of the war ravaged country while the Somali government forces backed by the almost 5,000 AU peacekeepers are partly in control of Mogadishu.

(Xinhua News Agency August 21, 2009)