Eight Yemeni soldiers, including a senior officer, have been killed in an ambush by militants in the restive and oil-rich Marib province, Press TV reported.
The Saturday attack took place as troops were visiting a main oil pipeline that had been destroyed in another attack on December 6, The Associated Press reported.
In a statement, the Yemeni defense ministry called the assault a "terrorist ambush," confirming that the chief-of-staff for Yemen's central military region was killed.
The officials said they believed the militants in the attack were from al-Qaeda terrorist organization.
The Yemeni army began an offensive last week in the Marib to target militants, who had repeatedly attacked the pipeline and power lines in recent weeks.
Al-Qaeda in the Arabian Peninsula has taken advantage of the weakness of the Yemeni central government during about a year and eight months of anti-government demonstrations to expand their presence in the impoverished country.
Al-Qaeda loyalists have carried out a spate of deadly attacks against Yemeni security forces since Ali Abdullah Saleh's successor, President Abdrabuh Mansur Hadi, came to power in February 2012.
In May, the Yemeni military launched an all-out offensive and retook a string of towns in Abyan province, where al-Qaeda loyalists had established themselves.