MOGADISHU: Fighting between government soldiers and Islamic insurgents killed at least 15 people in central Somalia on Thursday as the warring sides tried to gain ground in strategic towns.

Witnesses also reported seeing troops from neighboring Ethiopia roll into the country — a development that would enrage insurgents who saw Ethiopia as an occupying force after it helped drive out Islamists in 2006.

The fighting started Thursday in Bula Burte, about 130 miles (210 kilometers) north of the capital, Mogadishu, when government soldiers moved into the town controlled by the insurgent group al-Shabab. The United States says the group has ties to al-Qaida, which al-Shabab denies.

Local resident Osman Ganey said he saw 15 corpses and that the fighting was continuing.

"We closed all our shops and most of the residents are fleeing from the town," a local businessman, Mohamed Ibrahim, told The Associated Press by telephone.

Also Thursday, al-Shabab fighters moved into Belet Weyne, near the border with Ethiopia, forcing government soldiers to retreat to the far side of town. The insurgents moved in after witnesses spotted Ethiopian troops there, identifying them by their uniforms and their trucks with Ethiopian license plates.

Ali Mohamed Gedi, a spokesman for the regional government, denied Ethiopians were in the country.

"There was no big fighting but the government soldiers have left the western part of Belet Weyne and the al-Shabab men are in control," said local resident Daud Haji Ibar.

Controlling Belet Weyne is vital from a military standpoint because of the town's proximity to Ethiopia, which has sent troops here in the past to stop Islamists from taking power. It also serves as a link between southern Somalia and the agriculturally rich central region.

Somalia has been ravaged by violence and anarchy since warlords overthrew dictator Mohamed Siad Barre in 1991, then turned on each other. Al-Shabab, which has foreign fighters in its ranks, operates openly in the capital and seeks to overthrow the government and impose a strict form of Islam in Somalia.