WARNING: Video contains graphic images of whale slaughter which may disturb
Reports that Japanese whaling has occurred in New Zealand's sovereign waters are wrong, Foreign Affairs Minister Murray McCully says.
Anti-whaling group Sea Shepherd is pursuing the Japanese fleet after finding all five of its vessels in the Southern Ocean, along with evidence of whale kills.
The Sea Shepherd fleet, comprising the Steve Irwin, the Bob Barker and the Sam Simon, is now trailing the Japanese ships in a bid to disrupt or shut down their whale-killing operations.
Sea Shepherd says it spotted the Japanese vessel, Nisshin Maru, in New Zealand's sovereign waters in the Ross Dependency Antarctic region and inside the internationally recognised Southern Ocean Whale Sanctuary.
But Mr McCully says these are not New Zealand's sovereign waters.
"New Zealand has responsibility for co-ordinating search and rescue operations in a large area in the Southern Ocean, however, these are international waters and not within New Zealand's maritime jurisdiction," he said.
Mr McCully condemned the resumption of so-called scientific whaling in the Southern Ocean.
New Zealand has repeatedly called on Japan to end its whaling programme.
"The practice of whaling in the oceans south of New Zealand is pointless and offensive to a great many New Zealanders," Mr McCully said.
The Sea Shepherd group says it has footage of three dead protected minke whales on the deck of the Nisshin Maru, taken when the factory ship was first found.
A fourth whale, also believed to be a minke, was being butchered on the deck.
Last June, the New Zealand government joined the Australian government's challenge to the legality of Japan's whale hunt in the Southern Ocean Whale Sanctuary at the International Court of Justice.
A judgment in the case is yet to be delivered.