Six suspected al Qaeda militants and three Yemeni soldiers were killed in clashes in Yemen's eastern region of Hadramout on Monday, the defence ministry said.
Last year, the Yemeni army, with U.S. backing, drove al Qaeda militants and their allies from some of their southern strongholds. But the insurgents have since regrouped and mounted attacks on government officials and installations.
Maintaining stability in impoverished Yemen, which is also struggling with southern separatists and northern rebels, is a priority for Washington and Gulf states because of its proximity to major shipping routes and Saudi Arabia, the world's top oil exporter.
The militants attacked an army checkpoint at the western entrance of Sayoun, Hadramout's second-largest city, killing three soldiers. Six suspected al Qaeda fighters also died in the exchange of fire, the defence ministry said on its website.
Al Qaeda in the Arabian Peninsula (AQAP) is one of the most active branches of the network founded by Osama bin Laden, and militants have launched attacks from there against the West.