Dozens of armed tribesmen stormed a police station and a central prison in Yemen's southern province of Lahj early Tuesday, releasing 20 prisoners, security officials said.
Two groups of tribesmen raids the two sites, which share one buliding in Tuban district, and freed 20 prisoners following clashes with guards around the building, the official told Xinhua on condition of anonymity.
No casualties have been reported, he added.
One of the guards said they were unable to counter the heavy shootings by the armed tribesmen, who were backed by members of the separatist Southern Movement in Lahj, and finally surrendered.
Lahj, some 337 km northwest of the capital Sanaa, is a key stronghold of the Southern Movement.
South and north Yemen unified peacefully in 1990, but the relationship deteriorated in 1994, when southern insurgency was quelled in a civil war.
Calls for separation have been renewed since early 2007