A Yemeni security official says militants have assassinated two senior officers in drive-by shooting south of the capital.

The official says that one intelligence officer and the deputy security chief of the city of Damar, nearly 100 kilometers south of Sanaa, were killed Thursday in the city when militants riding motorcycles opened fire at their moving cars.

The official spoke on condition of anonymity because he was not authorized to speak to the media.

Officials believe that al-Qaida is waging a retaliation campaign against top officials after a military offensive pushed its militants out of their strongholds in southern Yemen in May. The group took control of large swath of land during last year's uprising.

Washington considers Yemen's al-Qaida branch as the group's most dangerous offshoot.