Anti-whaling activist Paul Watson has accused Foreign Minister Murray McCully of endangering the lives of activists in Antarctica by implying that they were trying to kill Japanese whalers.

Mr McCully said in a radio interview: "If people are determined to break the law and determined to kill other people on the high seas, then it is not the responsibility of the New Zealand Government or any other Government to send armed vessels down there or something of that sort to stop them."

Mr Watson, the founder of the radical group Sea Shepherd Conservation Society, said he found Mr McCully's remarks "totally offensive".

"For 33 years I've been protecting whales without causing a single injury to a single person and when some know-nothing politician comes out and accuses me of trying to kill somebody I do get upset."

Sea Shepherd has had three boats, the Steve Irwin, the Bob Barker and the Ady Gil, in Antarctica trying to stop the Japanese whaling fleet from hunting whales.

The showdown between Mr Watson and Mr McCully comes after theNew Zealand-registered trimaran Ady Gil, formerly known as Earthrace, sank after a collision with Japanese security ship, Shonan Maru No 2.

Mr Watson said the minister's comments had "put our lives at considerable risk".

"Statements from politicians in Australia and New Zealand have given a green light to the Japanese to do whatever they want to down here.

"If they know they can sink a New Zealand-registered vessel and get away with it, they are going to escalate their violence against us," Mr Watson said from Antarctica last night.

The veteran activist, who split from Greenpeace decades ago because its anti-whaling protests were too passive, admitted sinking eight whaling ships in his career, but he insists that no one was injured.

"We're not a protest organisation. We take action against poaching operations and I see nothing wrong with sinking a vessel that's involved with illegal exploitation of an endangered species."

Mr Watson claimed Mr McCully's first duty was to "whore himself out to foreign trade agreements with countries like Japan".

"I find it incredible that a New Zealand-registered vessel with a New Zealand crew was rammed and sunk by a Japanese whaler and New Zealand is not going to come to arrest that vessel or bring charges against it."

Meanwhile Peter Bethune, the captain of the Ady Gil, has denied ramming the Shonan Maru No 2.

The $1.5 million Ady Gil sank yesterday morning while being towed to a French research station.

Mr Bethune said he was still jittery from what he believed was a deliberate attack on his boat.

"We came down here looking for a fight. I expected them to retaliate but I didn't expect them to sink our ship. There is no question they steered directly at us."

The bow of the Ady Gil was sheared off in the collision and one of the six crew suffered two broken ribs.

Mr McCully has called for restraint from protesters and whalers as New Zealand, Australian and Japanese authorities begin an investigation.

The Institute of Cetacean Research, which represents the Japanese fleet, said its ships had never deliberately rammed a vessel. Spokesman Glenn Inwood claimed footage of the crash showed the Shonan Maru No 2 was trying to avoid colliding with the Ady Gil.

"I believe the Ady Gil miscalculated and entered into the path of the Shonan Maru."

He added that Japanese security ships would do all they could to protect their research vessels.