(Adds background) By Nick Tattersall LAGOS, Sept 20 (Reuters) - The main militant group in Nigeria's oil-producing Niger Delta said on Saturday it had destroyed a major oil pipeline belonging to Royal Dutch Shell <RDSa.L>, the latest strike in its campaign against the industry. The Movement for the Emancipation of the Niger Delta (MEND) said it had attacked the pipeline at Buguma Front in Rivers state late on Friday. It was not immediately possible to confirm the attack. "MEND will continue to nibble every day at the oil infrastructure in Nigeria until the oil exports reach zero," the group said in an e-mailed statement. MEND has launched attacks on pipelines, flow stations and oil and gas facilities in the world's eighth biggest oil exporter almost every day over the past week. Oil output in Africa's top producer has fallen by 150,000 barrels per day because of the violence and Shell has warned the upsurge in violence is likely to weigh on its quarterly earnings. Oil prices, which had been dropping on fallout from the global credit crisis, have edged higher on supply concerns linked to Nigeria's deteriorating security situation. Prices traded above $100 on Friday. Militants say they are fighting for greater development and a better living environment after decades of neglect in the delta, a vast network of mangrove creeks spilling into the Atlantic Ocean. But the unrest is fuelled by a lucrative trade in stolen oil, known as bunkering, and the line between militancy and rank criminality is blurred. The militants have mostly focused their attacks on Shell-operated installations, sabotaging their pipelines, gas plants and flow stations. Some Chevron <CVX.N> facilities have also been targeted. (Editing by Mark Trevelyan)
