Somalia's militant group Al Shabaab retook the southern Somali town of Hudur following the withdrawal of allied Ethiopian and Somali government troops based in the area, residents said.

Reports from the region indicate that the fighters arrived in Hudur just hours after the Ethiopian and Somali government troops left and no fighting took place over control of the key town.

Hudur, provincial capital of Bakool region has been under the control of Ethiopian and Somali government forces for the past two years after Ethiopian troops crossed the border into Somalia to chase the rebel fighters from the city.

"Hudur is in the hands of Al Shabaab fighters. The government troops and the Ethiopian left last night (Saturday) and Al Shabaab came early in the morning," a resident in Hudur, who asked not to be named, told Xinhua.

Reports from Bakool say that Somali government troops and Ethiopian forces were regrouping on the outskirts of Hudur and that the town remains tensely calm. Residents have began fleeing for fear of battle between the two sides.

This is the first key Al Shabaab gain since they were ousted in most towns in central and southern Somalia including the capital Mogadishu and the strategic port city of Kismayo.

Ethiopian troops crossed over into Somalia in 2011 to give support to Somali government forces and African Union peacekeepers in the horn of Africa nation.