"Armed tribesmen of a powerful tribal coalition, Bani Dhabian and Jihm, bombed the oil pipeline in Serwah city and exploded the country's main electricity grid, causing mass blackout in other provinces including the capital Sana'a," the official told Xinhua by phone.
"They also attacked an army checkpoint, killing four soldiers and burning a military vehicle," the official said Monday on condition of anonymity.
"The tribesmen have accused several officers of the military units stationing in Serwah of shooting and killing six members of their clan in the past two weeks and demanded that they should be brought to justice," he said, adding that mediation between the two sides has failed and that the attacks came in revenge against the army.
Yemen has seen frequent attacks by al-Qaeda militants and armed tribesmen on power grids and oil pipelines, which carries about 110,000 barrels of crude oil everyday to the main oil export terminal on the Red Sea, since the eruption of uprising against former President Ali Abdullah Saleh in 2011.
In December 2012, the army launched a massive offensive that left at least 10 tribesmen killed and more than 15 others injured.
The cash-stripped Yemeni interim government depends on oil exports for up to 70 percent of its budget.