Adria pipeline, pipeline completed in 1974 to carry Middle Eastern and North African crude petroleum from the deepwater port of Omisalj on the island of Krk, in Croatia, to inland refineries. The pipeline connects refineries in Croatia, Bosnia and Herzegovina, Serbia, and Slovenia—including Sisak, Bosanski Brod, Novi Sad, Pančevo, and Lendava—with the Adriatic Sea. From Sisak a separate pipeline carries oil to Hungary. The segment of the pipeline from Omisalj to Sisak is 36 inches (91 cm) in diameter, and from Sisak to Hungary it is 28 inches (71 cm). The possibility of reversing the flow of the Adria pipeline and linking it with the Druzhba pipeline in Hungary—thereby allowing Russia to more easily export its vast oil supplies—has been under consideration since the 1990s. Although six countries signed a 2002 agreement to join the pipelines, environmental concerns stalled its development.