Hard-line Somali Islamist fighters captured another town after a pro-government militia abandoned it, officials and residents said.

The Islamists' victory gained them territory near a key route linking government troops in the capital with allied militias in central Somalia.

An Islamist offensive launched earlier this month has claimed over a hundred lives in the capital and raised fears that Al Qaeda-linked insurgents could overthrow the U.N.-backed government, giving terrorists a safe haven on the Horn of Africa and imperiling anti-piracy efforts.

Resident Hassan Muhumed said militia members abandoned the small town of Mahaday, 70 miles north of the capital of Mogadishu, when they heard the Islamists were coming. Resident Fahad Abdulahi said the Islamists were driving around town with loudspeakers urging residents to attend a rally.

Sheik Hassan Mahdi, a spokesman for the Islamic Party group, confirmed his fighters had taken Mahaday unopposed. The Islamic Party is a coalition of forces fighting alongside al-Shabab, a group whose leaders the U.S. State Department has tied to Al Qaeda.

Somalia's presidential spokesman, Abdiqadir Osman, said government troops had mounted a strategic withdrawal.

"Our troops were not defeated. No fighting took place," he said. "We have withdrawn from the city because of military tactics and will return to it when we want to."

The insurgents seized the nearby provincial capital of Jowhar in central Somalia on Sunday. Jowhar lies on the same key road.

Somalia's new president — a former Islamist fighter himself — has invited the insurgents for power-sharing talks and instituted Shariah law in an attempt to win over his former allies. So far the Islamists have refused to meet him.

Somalia is torn apart by warring clans and has not had a functioning government since 1991.