Tribesmen bombed Yemen's main oil pipeline in the central Maarib province yesterday, a government official said, the fourth attack on the pipeline in a month.

The blast, which stopped oil flows to the Ras Isa oil terminal on the Red Sea, caused a fire and damage to the pipeline about 25 miles from where it starts in Maarib. No casualties were reported. The pipeline was set on fire earlier this month after threats by a Yemeni tribe after a siege on its leader's house by security forces. Tribesmen often do this to put pressure on the government. Yemen has one of the most active franchises of al-Qaeda.