Fuel oil leaked into Poland's Vistula river for the second time in a week Sunday, causing a roughly 20-kilometer (12-mile) slick, AP quoted authorities as saying. A spokesman for the state pipeline operator PERN, Krzysztof Zalewski, said the reason for the spill between the central towns of Wloclawek and Ciechocinek had not yet been determined, but was likely the result of a hole in a section of pipeline. A similar spill occurred on Dec. 10 in the same area. The underwater pipeline links a refinery in Plock, in central Poland, with storage facilities some 120 kilometers (75 miles) away.