At least four police members were injured Saturday in a gunbattle with pro-secession gunmen in Yemen's southern port city of Aden, a security official said.

The battle broke out when police troops attempted to dismantle a tent camp of pro-secession southern activists and reopen blocked roads in the Mansoura district in Aden, the local security official told Xinhua on condition of anonymity.

"The secessionist gunmen intercepted some police vehicles, sparking a short shootout that left 4 policemen injured," the security official said.

"Police troops are determined to remove roadblocks and reopen two major streets that have been closed for several months," he added.

Witnesses told Xinhua anonymously that several armored vehicles stormed the Martyr's Square camp in the Mansoura district.

"Many soldiers are now stationing inside the camp after several hours of fighting with the gunmen," the witnesses said.

The port city of Aden is a main stronghold of youth activists demanding independence for the south.

North and South Yemen unified peacefully in 1990, but the relationship deteriorated in 1994. Calls for separation in the country's southern regions were renewed in 2007.