MOGADISHU, Mar 11 - Intense fighting between Somali government forces and Islamist insurgents on Wednesday left 23 civilians dead in Mogadishu, a medical source and witnesses said.

Shebab militants, linked to al-Qaeda, used heavy artillery to target government positions in the north of the capital.

Government troops counter-attacked later in the day, buttressed by armoured vehicles from African Union peacekeepers.

Both sides claimed victory.

"We have recovered the bodies of 17 other civilians as well as 65 wounded," the head of Mogadishu's ambulance service told AFP.

Three other civilians were killed in crossfire, witnesses said, while officials earlier said they had collected three bodies that morning.

Among the casualties, nine were killed by an exploding shell, witness Muhidin Adan Idris said.

"There were pieces of human flesh everywhere. It was horrible," he said.

Belligerent factions in Mogadishu have been locked in a tense stand-off for weeks, amid expectations of an imminent offensive by the government and its African Union backers to wrest Somalia back from the insurgency.