Military and security officials in Yemen say a suspected U.S. drone strike has killed five suspected al-Qaida militants traveling in a vehicle near the extremist-held coastal city of Mukalla.

The officials said the attack Wednesday happened east of the city. Al-Qaida's Yemen branch, considered by Washington to be the most dangerous offshoot of the terror network, has made gains in the sprawling eastern Hadramawt province, capturing its capital, Mukalla, in April.

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

Al-Qaida has made advances amid the civil war now engulfing Yemen. Washington meanwhile has kept up its drone attacks there targeting al-Qaida militants, including one that killed the group's top leader in Mukalla in June.