Pirates have seized a Greek-run oil tanker off the coast of Nigeria. Greek maritime officials on Monday said that the Aegean Star and its 20-member crew were hijacked in the Gulf of Guinea. They said the ship was carrying oil from Ghana to Benin when it was seized 55 kilometers off the Nigerian coast.The ship's crew is said to include three Greeks and sailors of other nationalities. There has been no word on their condition. The Liberian-flagged ship is operated by Greece-based Endeavour Marine Company.