Armed tribesmen along with separatist gunmen took control over the whole Yemen's southern province of Lahj on Thursday, seizing all government buildings and facilities in the province, local officials told Xinhua.

Fierce clashes between the security forces and armed tribesmen supported by separatists gunmen ended with forcing the soldiers to hand over all government complexes in the city, the official told Xinhua on condition of anonymity.

Separatists gunmen belonging to the separatist Southern Movement have already seized al-Milah, the second-largest district in Lahj along with a number of other districts, the official said.

All entrances of the province were controlled by either armed tribesmen or the separatist gunmen after the withdrawal of al- Qaida militants late on Wednesday, he added.

A member of the separatist Southern Movement told Xinhua that taking control over the whole province aimed at "preventing the Yemeni security authorities from handing government buildings to al-Qaida militants."

South and North Yemen unified peacefully in 1990, but the relationship had deteriorated by 1994, when a southern insurgency was quelled in a civil war. Calls for separation were renewed in 2007.