US conservation group Sea Shepherd has vowed to fight a US court order to stay at least 450 metres away from Japanese whaling ships, and to keep protecting whales "with our ships and our lives". The injunction was ordered by the US Court of Appeals for the Ninth Circuit, in the latest step in a legal battle between the anti-whaling group and Japanese authorities over vessels in the Southern Ocean. It said Sea Shepherd and Canadian militant conservationist Paul Watson, who is wanted by Interpol, "are enjoined from physically attacking any vessel engaged by plaintiffs," including Japan's Institute of Cetacean Research. In addition, they are banned from "navigating in a manner that is likely to endanger the safe navigation of any such vessel," said the order, issued on Monday. "In no event shall defendants approach plaintiffs any closer than 500 yards (450 meters) when defendants are navigating on the open sea," it added. The joint plaintiffs are Kyodo Senpaku Kaisha, Tomoyuki Ogawa and Toshiyuki Miura. In a statement, the Institute of Cetacean Research and Kyodo Senpaku said they "welcome" the injunction, which remains in force until the US court issues its opinion on the currently pending appeal. The groups said they had asked the court to expedite its review because Sea Shepherd had "launched its sabotage vessels and announced its intention … to take physical action against the Japanese research vessels."