At least five militants were killed and three soldiers wounded in Yemen on Tuesday in fighting near a damaged oil pipeline east of the capital Sanaa, a defense ministry official and residents said, Reuters reported.
In a separate incident, two gunmen riding a motorbike shot dead Brigadier Fadel Mohammed Ali, an adviser to the minister of defense, outside the ministry's offices in Sanaa, a police source said. Further details were not immediately available.
The fighting in turbulent Maarib province broke out when government troops backed by air strikes tried to secure the pipeline and repair damage inflicted last month by local militants, the official said.
Yemen's oil and gas pipelines have repeatedly been sabotaged by Islamist fighters or tribesmen since an uprising erupted last year, causing fuel shortages and slashing export earnings for the impoverished country.
The country's stability is a leading security goal for the United States and Gulf Arab allies because of its strategic position next to top oil exporter Saudi Arabia and shipping lanes, and because it is home to one of the most active wings of al Qaeda.
Under an agreement reached earlier this month between tribal chiefs and the government, tribes in Maarib were meant to stop militants from attacking the pipeline in return for a halt to air strikes in the area.
A local official said troops were deployed on Tuesday after tribesmen failed to secure the pipeline or to hand over fighters involved in the killings of 17 army officers and soldiers in an ambush earlier in December. They were killed while inspecting the pipeline.
The affiliation of the militants in Maarib is unclear. Local sources said some had links to al Qaeda, while others were involved in kidnapping foreigners to pressure the government to release jailed kinsmen.