The Yemeni army launched an assault on Sunday using tanks and rockets on tribesmen blocking repairs to the country's main oil export pipeline, tribal sources said.
Earlier this month, the military launched a major offensive against tribesmen suspected of repeatedly blowing up the Maarib pipeline and attacking power lines. At least 17 soldiers were killed in an ambush by suspected al Qaeda militants.
"Armed tribesmen prevented repair teams from fixing the oil pipeline and army forces shelled the areas where the gunmen are based using tanks and Katyusha rockets," a tribal source told Reuters. There were no immediate reports of casualties.
Local authorities reached a deal last week with tribal leaders under which the military will cease air strikes and the tribesmen will chase those responsible for killing the soldiers. The U.S.-allied Yemeni government depends heavily on tribesmen in its fight against Islamist militancy.
Yemen's oil and gas pipelines have repeatedly been sabotaged by insurgents or disgruntled tribesmen since anti-government protests created a power vacuum in 2011, causing fuel shortages and slashing export earnings for the impoverished country.
Yemen's stability is a priority for the United States and its 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.
A U.S.-backed military offensive has driven the militants out of areas they seized in the south last year but has not prevented them from launching attacks that have dealt damaging blows to the army and security apparatus.
Before the attacks, the Maarib pipeline had typically carried 110,000 barrels per day (bpd) of light crude to the Ras Isa export terminal on the Red Sea coast.
A long closure of the pipeline last year forced the country's largest refinery at Aden to shut, leaving the small producer dependent on imports and fuel donations from Saudi Arabia.