MOGADISHU, Somalia (AP) — An Islamic militia that the U.S. considers a terrorist organization took over two strategic towns in Somalia on Tuesday, the latest territory grab by a strengthening insurgency, officials said.

The militia, al-Shabab, seized El Dheer in central Somalia and Qoryoley in the south as part of a burgeoning campaign to take territory nominally held by the weak U.N.-backed government and its Ethiopian allies. The new seizures give the group a strategic base in central Somalia, where it controls Kismayo, the third-largest city.

Al-Shabab, which means "the youth," is the military wing of Union of Islamic Courts, an Islamic party that ruled much of the country in the second half of 2006 and aims to impose Islamic sharia law in Somalia. It launches daily attacks on Somali government forces and their Ethiopian allies.

The U.S. says many of its leaders are linked to al-Qaida.

Al-Shabab fighters took over El-Dheer, a crossroads linking southern, central and northern Somalia on Tuesday, according to Sheik Ali Dhere, the group’s spokesman. The town is 210 miles (340 kilometers) north of the capital of Mogadishu.

"The town seems to be under the full control of al-Shabab," local human rights worker Mohamed Gule Hassan told The Associated Press. "After 24 hours of tension and fear in the town, which forced hundreds of people to flee from their homes, the fighting ended."

In a separate attack, nearly 1,000 insurgents seized Qoryoley in southern Somalia from militias loyal to Somalia’s crumbling government. "They opened fire on our checkpoints and after we realized they were more mobile than us we decided to withdraw," said the town’s police chief, Nor Shakow Jibril.

The civil war between Islamists and the transitional government is complicated by intricate webs of clan loyalty and the involvement of rival Eritrea, which supports the Islamists, and Ethiopia, whose troops shore up the government.

Al-Shabab has been fighting since 2006, when the Union of Islamic Courts was ousted by Ethiopian troops who sparked a rebellion to support the government. Since then, more moderate members of the Islamic courts have signed an ineffectual peace deal with the government.

Somalia has not had a functioning government since warlords overthrew a socialist dictator in 1991. The current government comes under daily attack in the capital and its forces are badly trained, equipped and often unpaid.