Yemeni security officials in the government-controlled southern port city of Aden say suspected al-Qaida gunmen have broken into the city's main prison, freeing an individual suspected of attacking the compound of Aden's former governor in August.

The officials told the AP on Sunday that the gunmen carried out the operation overnight.

Four people were killed in the August rocket-propelled grenade attack on the former governor's compound. The former governor and other officials who were present at the time were not hurt.

The officials spoke on condition of anonymity because they were not authorized to talk to reporters.

Yemen has been embroiled in fighting between Shiite rebels and allied army units against forces loyal to the internationally recognized government as well as southern separatists and other militants.