Eight Yemeni soldiers including a senior officer were killed in an ambush by militants while visiting a main oil pipeline that had been destroyed in an earlier attack, the defense ministry said.
In a statement, the ministry called the Saturday attack in Marib province a "terrorist ambush," confirming that the chief-of-staff for Yemen's central military region was killed.
Security officials said earlier that they believed the militants in the attack were from al-Qaida. The army began an offensive last week in the restive, oil-rich province east of the capital to target militants who had repeatedly attacked the pipeline and power lines in recent weeks. The officials spoke on condition of anonymity because they were not authorized to release the information.
The militants stole six military vehicles in the ambush.
The U.S. considers the local al-Qaida branch the world's most active. The U.S. has helped Yemen intensify its campaign against militants.