Gunmen, believed to be from the southern secessionist movement, Harak, took over a military post in Yemen's southern Dhale province on Friday, informed sources told the Yemen Post.
The post is based on the peak of the highest mountain in the province and fierce battles erupted between the forces and the gunmen, the sources said.
"The attack on the military post took place during the prayers on Friday when the gunmen exploited the absence of the troops who were at mosque," they said.
Furthermore, the gunmen besieged another nearby military post and the forces were fighting them to retake the seized one, the Dar Al-Haid camp, and lift the besiege, they added.
The southern movement, Harak, emerged in 2007 to demand legal rights of the people in the south but later it turned to be divided into wings including armed ones.
Separately, the army is preparing to storm from all directions Zinjibar, the capital of Abyan, to clear militants from the remaining areas, after the forces in association with popular fighters have recently regained control of some areas in it. Al-Qaida militants seized Zinjibar and other towns in Abyan last year.
In southern and southeastern regions, the army, with direct support from the US, has been fighting Al-Qaida militants, mainly in Abyan and Shabwa, for the past few years.
Hundreds of militants have been killed and injured in the past few weeks including senior militant leaders wanted by the US. Some of the leaders were killed in drone strikes in Shabwa.