Duelling videos: Whalers and Sea Shepherd release rival clips

Sea Shepherd and the Japanese whaling fleet's battle has moved from the Southern Ocean to the video editing suite.

The activist group and Japan's Institute of Cetacean Research (ICR) have released rival clips of the crunching collisions between their vessels after the dangerous confrontation reignited yesterday.

The Japanese fired the first shot, releasing footage that appeared to show the Bob Barker ramming its factory ship the Nisshin Maru and the Korean tanker Sun Laurel.

The ICR said the ships were hit five times by the Bob Barker and another Sea Shepherd vessel, the Sam Simon, yesterday.

It said activists had used inflatable boats in an attempt to entangle the rudder and propeller of one of its ship with wire ropes and to plug the drains on the Nisshin Maru.

"This time, SS (Sea Shepherd) is sabotaging refuelling operation, which is essential for the safe navigation of ships, and the sabotage is not only malicious but inconceivably obstructive actions," an ICR statement said.

"Thus it threatens safety of our research ships and lives of crews on them and is therefore completely unacceptable."

The ICR said damage was being assessed.

Sea Shepherd hit back by releasing YouTube footage it said showed the Bob Barker being "sandwiched" by the Nisshin Maru and Sun Laurel as it blocked a third attempt at refuelling.

The clip appears to be a longer version of the same collision captured by the whalers, but Sea Shepherd officials were unable to confirm that.

The conservation group says its footage shows the Bob Barker had right of way.

"What they're doing is taking a selective snippet," Sea Shepherd director Bob Brown told AAP.

"You can see in that footage the very small Sea Shepherd ship being tossed around (as if) in the washing machine."

Another video posted by Sea Shepherd shows a fiery flash, allegedly caused by a concussion grenade thrown by whalers, while Steve Irwin captain Paul Watson claimed "commandos" had been dropped on the Korean tanker by a Japanese military-style ship in the area, the Shirase.

Dr Brown said three armed Japanese customs officials had been dropped on to the tanker by helicopters.

"They've been dropped on that ship I believe and we see flash grenades going off," he said.

"(The Shirase is) there certainly for intimidation."

Federal Environment Minister Tony Burke said the Shirase had previously conducted research in the area with Australian co-operation.

But he said he had sought assurances from the Japanese government that the ship had not been involved in assisting the whaling fleet.

"I continue to urge everybody in the Southern Ocean to recognise safety at sea," Mr Burke said.

The ICR said Sea Shepherd had breached a US court order banning it from approaching the whaling fleet and denied its ships were illegally carrying heavy fuel in the pristine waters around Antarctica.

Dr Brown said conditions were making refuelling difficult, but more clashes were possible.

"It is extremely dangerous and, of course, I'm concerned for the safety and the wellbeing and the lives of the men and women that are down there," he said.

"But they are committed to protecting the whales and upholding the law."