BAGHDAD - Violence gripped southern Iraq Friday, with a bomb attack on a main oil pipeline extending to the Al Dawra oil refinery in the capital Baghdad.Assem Jihad, spokesman for IraqÂ’s Oil Ministry, said an explosive device was planted underneath the pipeline, which begins in the Udwaniya region, the independent Voices of Iraq (VOI) news agency reported Friday. The explosion caused several fires which engulfed the area with clouds of smoke. The attack is expected to productivity of the Al Dawra refinery, which has a capacity ranging from 110,000 to 130,000 barrels a day.