Nigeria plans to increase crude oil production capacity to four million barrels a day by 2020 and expand its reserves to 40 billion barrels, Petroleum Minister Diezani Alison-Madueke said. Africa\'s largest oil producer also aims \"in the years ahead\" to boost output of liquefied natural gas by another 20 million metric tonnes a year from the current level of 26 million tonnes, she said in a speech delivered at Howard University in Washington, Levi Ajuonuma, a ministry spokesman, said Friday. Nigeria pumped 2.1 million barrels a day of oil in April, according to data compiled by Bloomberg. Oil reserves currently stand at an estimated 37 billion barrels and its gas reserves are estimated at 187 trillion cubic feet, Ajuonuma said. \"With expansion of cap-acity by almost one million barrels per day over the next few years, Nigeria can significantly contribute to global supply additions and diversification, thereby alleviating the challenge of supply concentration around the Middle East,\" she said. Attacks by militant groups in the Niger Delta cut crude output by more than 28 per cent between 2006 and 2009, according to data compiled by Bloomberg. Disruption eased after thousands of fighters, seeking a greater share of oil revenue for the region\'s inhabitants, laid down their weapons and accepted an official amnesty. Nigeria\'s Movement for the Emancipation of the Niger Delta refuses to disarm, saying the government hasn\'t met its demands for control of the delta\'s oil.