Somali and African Union forces said they seized control Monday of a strategic town from Shebab Islamist fighters, in the latest military advance against the extremists.

Hundreds of Somali and Ethiopian troops with the AU force in Somalia (AMISOM) entered the town of Tiyeglow in the southwestern Bakool region, some 240 kilometres (150 miles) north of Mogadishu, with the Islamists fleeing ahead of the advance.

"Somali and AMISOM troops have captured Tiyeglow and forced the militants to leave without fighting," said government security official Mohamed Moalim.

"The operations will continue until the whole region is liberated."

Bakool had been a former stronghold region of the Shebab, who once controlled most of southern and central Somalia.

But the hardline fighters have been driven out of positions in Mogadishu and Somalia's major towns by the 22,000-strong AMISOM force.

AMISOM confirmed the town's capture, saying it had been the last town in Bakool the Shebab had held.

The Al-Qaeda-linked insurgents admitted the loss of the town but vowed to launch attacks.

"The mujahedeen fighters tactically withdrew from the town and the enemy entered," a Shebab military commander Sheikh Mohamed Ibrahim told AFP by telephone.

"I assure you that the area will be turned into their graveyards, they will never sleep in peace."

Local resident Hassan Adan said he had seen dozens of military trucks belonging to the Ethiopian army enter the town.

"There was no fighting at all, the Ethiopian troops entered the town with dozens of military trucks and tanks," Adan said. "Many people also left the town before they entered."

AMISOM and government troops are readying to attack and capture key southern areas still in Shebab hands, especially ports, to stem the Shebab's multi-million dollar trade in charcoal.

The fighting comes as UN and aid workers warn large areas of Somalia are struggling with dire hunger and drought, three years after famine killed more than a quarter of a million people.