Unknown attackers blew up Yemen's main oil pipeline that carries crude oil from the north-central province of Marib to a Red Sea export terminal Thursday, but export operations were not disrupted, DPA quoted security sources as saying today. The sources, who asked not to be named, said a technical team was assessing the damage to the pipeline that carries around 80,000 barrels of crude oil per day. It runs from the Safir oilfield in Marib, 190 kilometres north east of the capital Sana'a, to the exporting facility of Rass Essa in Houdieda province. The explosion occurred in the Arqain valley area, some 30 kilometres from Safir. An investigation into the attack was going on, the sources said. Yemen is a small non-OPEC oil producer that pumps around 330,000 barrels per day.