Somali residents say heavily-armed Ethiopian soldiers have crossed into central Somalia by entering a border town controlled by a pro-government militia.

"They came with battle wagons and trucks all full of soldiers and guns," said Hassan Abdi, a resident in the town of Balanbale in Galgadud region. "Everybody is very worried."

Ethiopian troops were setting up positions in the center of the town, residents said according to Reuters.

Central Somalia has been the scene of heavy fighting between insurgents and the pro-government groups.

"We are ready to fight the Ethiopians if they come close to our forces, we will give them a lesson," Hassan Maalin Takow, an al Shabaab commander told Reuters.

Al Shabaab and allied group Hizbul Islam is trying to oust the government of President Sheikh Sharif Ahmed --a former rebel who was elected in January-- and impose a strict version of Islamic law throughout the Horn of Africa's nation.

The insurgents control large swathes of the south and parts of the capital Mogadishu. They have been battling pro-government forces this month in a bid to increase their influence in the center of Somalia.

Ethiopia sent thousands of troops into Somalia in 2006 to help topple a rebel movement that controlled Mogadishu and most of the south. That drew protests from some in the Muslim world and enraged the insurgents, who regrouped and launch an insurgency campaign against the Ethiopians.

The Ethiopian soldiers withdrew in January but residents, insurgents and humanitarian organizations have reported several incursions in the past few months.

HSH/ZAP/DT