Italian oil giant ENI said Sunday that \"an act of sabotage\" has caused a spill at one of its pipeline in Nigeria\'s Bayelsa state, as local leaders condemned the company for not reacting swiftly. Oil theft is a worsening problem in Africa\'s top producer, where thieves often blast into pipelines in the Niger Delta region and then siphon off the crude to sell on the black market. \"Due to an act of sabotage yesterday night, there has been a spill along the flowline between Nembe and Obama,\" an ENI spokesman, who did not wantto be named, told AFP in Rome. The area, known locally as Obama fields, was renamed to honour US President Barack Obama. \"The repairs began today. The Nembe South wells have been shut down with minimal impact on production,\" the spokesman added. The spill has impacted some waterways and farms, authorities from the affected Nembe kingdom said in a statement, which also criticised \"multi-nationals\" for using \"delay tactics\" after spills. \"They allow the oil spill to spread to rivers and mangrove forests before coming for inspection and clean-ups,\" said the statement from Nengi James, Chairman of the Oil and Gas Committee of Nembe Kingdom. The UN released a report last year saying decades of oil spills in Nigeria may require the biggest cleanup ever undertaken, with communities dependent upon farmers and fishermen left ravaged. Pipeline sabotage aimed at stealing crude has been the major cause of recent onland spills. Roughly 150,000 barrels of oil and condensate is stolen in Nigeria each day, according to an April estimate by Shell chief executive Peter Voser. Nigeria, the world\'s eight largest oil producer, has been producing between 2.0 and 2.4 million barrels per day in recent months. The sector generates 90 percent of the country\'s foreign exchange earnings.