Two al Qaeda militants and two tribesmen allied to the army were killed in an attack on a military checkpoint in southern Yemen, tribal sources said on Tuesday.
Yemen's wealthier Gulf neighbours and the United States are concerned that al Qaeda and other Islamist militants operating in Yemen could pose a threat to neighbouring top oil producer Saudi Arabia and to nearby shipping lanes.
The four deaths occurred in the southern province of Abyan when a vehicle carrying armed al Qaeda militants attacked the army checkpoint, touching off a firefight, the sources said.
Shortly after the attack, another vehicle approached the same checkpoint and exploded in an apparent suicide bombing, killing its driver and wounding five tribal army-backers.
The Yemen-based al Qaeda in the Arabian Peninsula and other militant groups strengthened their grip on parts of the country during an uprising that ousted veteran President Ali Abdullah Saleh in February.
Washington, wary of the growing power of al Qaeda, has stepped up drone strikes on suspected militant positions, with the backing of Saleh's successor, President Abd-Rabbu Mansour Hadi.