The New Zealand-registered whaling protest ship Ady Gil, which collided on Wednesday with a Japanese whaling ship, has sunk while being towed, Sea Shepherd conservation society spokesman Paul Watson says.

Meanwhile, former Conservation minister Chris Carter - who took a prominent role when the whale wars in the Southern Ocean went awry in 2007 - says Foreign Minister Murray McCully's "passive role" in the latest debacle is putting the lives of protesters at risk.

Captain Watson told ABC Radio the crew of the Bob Barker - the Sea Shepherd group's newest ship to take to the waters - tried all day on Thursday to salvage the the $1.5 million vessel.



But attempts to tow the badly-damaged vessel failed and the crew was unable to keep it afloat.



Before the boat sank the crew removed all oil and fuel to avoid any pollution in the sea.



Captain Watson said the group had no other option other than to try and move the Ady Gil or abandon it.



"The Japanese harpoon vessels stayed close by but offered no assistance at any time."



Asked if they should have provided assistance, he said: "Well, they were responsible, they destroyed the vessel and the effort to try and keep it from polluting the ocean, I think, they should have offered some sort of assistance but they didn't.



"They refused to acknowledge any distress signal."

JoAnne McArthur/Sea Shepherd ADY GIL: The crew of a hi-tech anti-whaling trimaran rammed by a Japanese ship, describe it as attempted murder.

One of the Ady Gil's crew members broke two ribs in the collision.



Another of the group's vessels, the Steve Irwin, deliberately stayed away to avoid being tailed by the Japanese whalers, Captain Watson said.



He said the Steve Irwin was in pursuit of another Japanese harpoon vessel, the Yushin Maru, and the crew didn't want the whaling fleet finding out their location.



Both the New Zealand and Australian governments have called for restraint over the whaling stoush and for both sides to respect human life.



However Captain Watson said they wouldn't restrain themselves from protecting whales.



"I think that the governments have shown so much restraint themselves over the years they've done absolutely nothing."

Mr Carter said the National-led Government had been "largely silent" while Japanese whalers continue to use dubious science as an excuse to continue to hunt whales in the Southern Ocean.



He said the Government did not bother to send a minister to the recent International Whaling Commission meeting in Portugal for the first time in 10 years.



"That absence was a clear signal that the New Zealand Government now sees whale conservation as a minor issue," Mr Carter said. Mr McCully's "muted response" to Japanese whaling would damage New Zealand's position as a leading conservation nation.



Government officials met with representatives from the Japanese embassy in Wellington to discuss the sinking, with Japan reported to have said it regarded the incident as "regrettable" but a "low-key event".

But a spokesman for Australian Environment Minister Peter Garrett has told the ABC that neither the government nor the Australian Maritime Safety Authority received any request for help.



Australian Greens Senator Sarah Hanson-Young told ABC Television the Japanese should pick up the bill for the Ady Gil.



"Clearly we need the investigation to happen and obviously the Deputy Prime Minister (Julia) Gillard has said there will be one," she said.



"But the big problem is that the evidence that this investigation will draw on is simply going to be taken from the Japanese because Australia was not down there."



"The Australian Government have simply allowed this incident to happen by virtue of being absent in the entire activities of what's going on."

WHALING STOUSH

Japanese whalers and conservationists have squared off for more hostilities in the Antarctic, a day after the Ady Gil was crushed.

Sea Shepherd searched Antarctic waters by helicopter for a key Japanese whaling ship on Thursday, renewing its attempts to find and harass the whalers into giving up their hunt, Captain Watson said.

Japan kills about 1200 whales a year in Antarctica under what it says is a scientific programme allowed by the International Whaling Commission despite a broader moratorium on killing the mammals.



Critics say the programme is a front for illegal commercial whaling, and Sea Shepherd sends ships to Antarctica each season to try to stop the hunt - an effort portrayed on the Animal Planet TV series "Whale Wars."

On Wednesday, the Japanese whaling ship Shonan Maru plowed into the Ady Gil, knocking the bow off the wave-piercing trimaran speedboat that is one of the group's trio of vessels trying to harass the hunters out of business.

The whaling is conducted in international waters, but usually within the huge patch of ocean that is designated as Australia's maritime rescue zone and that Canberra considers a whale sanctuary.

But rules governing Antarctica are not clear cut. The frozen continent and the oceans around it are administered by agreement between nations, and there are conflicting claims about sovereignty.

"There is very little ability for a sort of police force to just turn up on the scene to separate the two sides" when then is a dispute such as Wednesday's clash, said Don Rothwell, a professor in international law at the Australian National University who wrote a recent report for the government on Antarctic whaling.

It was possible Sea Shepherd could try to sue the whaling ship's master for negligence in Wednesday's clash, he said. But the whalers could also try to have the Ady Gil charged with terrorism at sea for trying to foul its propellers with rope - a tactic Sea Shepherd openly says it uses.

Japan said it had asked countries that let the conservationists register their ships or use their ports to help curtail the group's aggressive acts. Sea Shepherd leader Paul Watson said Australia should send its navy or a customs vessel to stop what he calls illegal poaching.

But Wednesday's clash was unlikely to produce any useful change in policy, and had actually raised the chances of a further escalation in the whaling face-off, said Rothwell.

"This is the great fear at the moment," he said.

"Sea Shepherd is using very strong language, talking about a war with the Japanese," he said. "Increasingly, the Japanese have become more aggressive in their responses - we can expect that there will be more clashes."

Neither side show signs of backing down.

"The series of sabotage acts by the Sea Shepherd were very dangerous and risked the life and safety of the Japanese crew members," Japanese Foreign Ministry spokesman Yasuhisa Kawamura told reporters in Tokyo.

Watson vowed his group would not step back, saying "We now have a real whale war on our hands."

He said a helicopter from the group's main ship, Steve Irwin, was launched on Thursday to try to find the Japanese fleet's whale processing ship and resume attempts to disrupt the whalers.

Acting Australian Prime Minister Julia Gillard said there were no immediate plans to send a government vessel to the region. She said Canberra's ability to act was hampered because Japan did not recognise Australia's jurisdiction in the region.

"This is an issue where emotions run high," Gillard told reporters. "I am saying to everyone out in these dangerous and inhospitable waters that this is a time for calm judgments. We do not want to see people taking risks that result in a loss of life."

- with NZPA and AP