Anti-whaling nations on Thursday urged environmental activists not to take any action endangering human life as Japan's fleet prepared to set sail for its controversial annual hunt.
Australia, the Netherlands, New Zealand and the United States said in a joint statement that they respected the right to peaceful protests but would use the force of the law against any "unlawful activity."
The four nations "jointly condemn any actions that imperil human life at sea during the 2012-2013 Southern Ocean whaling season," said a statement, in line with previous years' messages, released by the US State Department.
The four nations also called on the vessels' operators to ensure safety.
The US-based environmental group Sea Shepherd each year disrupts the expeditions of Japan, which kills whales through a loophole in a 1986 global moratorium that allows "lethal research" on the ocean giants.
Sea Shepherd has vowed to fight a recent injunction from a US court, which, in response to Japan's complaints, ordered the environmentalists to stay at least 500 yards from the ships.
A Japanese official praised the court order, saying it would help "the whaling and research mission in the Antarctic Ocean to be conducted safely and smoothly."
The four nations reiterated that they were "resolutely opposed" to whaling in the waters, which the International Whaling Commission has declared to be a sanctuary.
"Lethal research techniques are not required in modern whale conservation and management," the statement said.