One of Yemen\'s main oil export pipelines carrying Marib crude was blown up on Thursday, cutting a flow of an estimated 125,000 barrels a day through the line to Ras Issa terminal on the Red Sea, officials said. \"An explosive device bombed the main oil export pipeline in Arqeen district of Marib province, to the northeast of the capital Sanaa, sparking a fire with clouds of black smoke,\" a provincial security official told Xinhua on condition of anonymity, hinting that the attack \"could be\" the work of al-Qaida militants. Meanwhile, the Defence Ministry blamed the attack for \" opposition-led armed tribesmen,\" who sided with the protest movement demanding the ouster of long-time President Ali Abdullah Saleh. The ministry said in a brief statement on its website that the attack came 24 hours after engineers repaired another subversive act on the same pipeline, which the ministry said was targeted by six separated attacks during the past 10 days. Trade and Industry Minister Hisham Sharaf said earlier that the government has lost nearly one billion U.S. dollars due to the attacks on the key oil pipeline. The impoverished Arab country has been in the grip of political unrest since the eruption of the nine-month-long pro-democracy protest calling for an immediate end to the 33-year rule of the embattled president. The unrest has affected foreign oil companies in the country, as well as paralyzed the normal life of the Yemeni people due to acute shortage in fuel supplies.