In a further setback for the weak interim government, a Somali warlord and hundreds of fighters defected from pro-government lines to join the Islamist forces on Wednesday.
Warlord, Muhammad Rooble Gobale, pledged allegiance to the Islamists together with 300 fighters, according to news reports.
The defection came three days after Islamists seized Kismayo, a strategic port city in southern Somalia. Islamists expect the move will strengthen their hold over the city.
Kismayo’s takeover was a severe blow to the Somali government. Islamists have said they will use their control over the port city to block the arrival of African Union (AU) peacekeepers into the country.
The city is located about 300 miles south of the capital Mogadishu, and is a possible arrival point for the peacekeeping forces.
The AU plans to send the first soldiers at the end of this month, but there are doubts regarding its effectiveness mainly due to a lack of resources.
Islamists are opposed to the deployment of an AU peacekeeping force, calling it an occupying force and vowing to fight it.
Islamists forced the Somali Transitional Federal Government (TFG) out of Mogadishu in June.