Osama bin Laden has training bases in Somalia and is intent on plunging the Horn of Africa country into further chaos, Somali Prime Minister Ali Mohamed Gedi said late on Sunday.

Gedi was responding to a purported audio recording by the al Qaeda leader that said a U.S.-backed bid to deploy foreign troops to Somalia would be part of a crusade to crush Islamic rule.

"It is clear that bin Laden is strongly involved in some areas in Somalia and has militant training bases," Gedi told a news conference in Baidoa, seat of Somalia's interim government.

"Bin Laden's not a Muslim leader, he's an extremist. Bin Laden is trying to plunge Somalia into chaos."

Gedi said the government would forcibly expel any foreigners found to be al Qaeda agents inside the Horn of Africa country.

"The TFG (transitional federal government) and Somali people will kick out these foreigners from Somalia," he said.

The interim government however has limited authority over Somalia. Formed in 2004, it has been based in the southern provincial town of Baidoa since February, too weak to move to the capital.

Bin Laden warned the United States and other countries against sending soldiers to Somalia, where Islamist militia won control of Mogadishu from U.S.-backed warlords last month.

Despite the message, the African Union agreed on Sunday to send troops to Somalia, which descended into lawlessness in 1991 when warlords ousted military dictator Mohamed Siad Barre.

A resolution adopted unanimously at a summit in Banjul said an AU peace and stability mission would be deployed in the wake of peacekeepers from the east African regional body IGAD.

Bin Laden also urged Somalis to back the Islamist movement which has also sought to extend its authority across the country and to fight interim President Abdullahi Yusuf and his allies.

The Islamist movement, known as the Council of Islamic Courts of Somalia, also oppose foreign forces, but were quick to distance themselves from bin Laden's comments.

Despite appointing hard-line cleric Sheikh Hassan Dahir Aweys -- on a U.S. list of al Qaeda associates -- as its leader, the Islamist movement denies links to terrorism or that it wants to impose Taliban-style rule in Somalia.