About 200 liters of diesel oil have leaked from a U.S. air base in southern South Korea, prompting local officials to scramble to stop the leak, witnesses and officials said Thursday. The oil leak at the U.S. military base in the port city Gunsan, 274 kilometers southwest of Seoul, was first detected by a local resident three days ago and was found to have spilled from a storage tank inside the base. Local government officials have used bundles of absorbent materials to prevent the oil slick from being poured into the Saemangeum sea dike on the west coast. \"Three days ago, I saw a slick of oil near Saemangeum,\" said local resident Choi Byeong-yong, who first detected the oil leak. \"As things got worse today, I reported (the oil) to the Gunsan city and maritime police,\" Choi said. The U.S. air base in Gunsan is home to the 8th Fighter Wing, which includes two F-16 squadrons and four other groups. While the amounts of the leaked oil are relatively small, the incident came amid growing concerns over possible environmental contamination at U.S. bases in South Korea. Last week, South Korea and the U.S. launched a joint probe to verify the allegations by American veterans that the U.S. troops buried large amounts of toxic chemical Agent Orange in the 1970s at Camp Carroll in Chilgok, 300km southeast of Seoul.