SEA Shepherd Conservation Society member Vincent Burke, in charge of crew safety aboard the Bob Barker, says confrontation is imminent as anti-whaling protesters gain on a fleet illegally poaching within a declared whale sanctuary.

"I can't give you a location as that's classified, but the Bob Barker is sailing in the Southern Ocean pursuing the Nisshin Maru factory ship.

"This ship processes the harpooned whales brought in by the killer ships. If we can block its slipway we can prevent the loading of whales," Mr Burke said.

This week, three Australian anti-whaling protesters who boarded the Shonan Maru 2 returned home to criticism of acting illegally and costing taxpayers hundreds of thousands of dollars.

Although the men are not associated with Sea Shepherd, Mr Burke defended the three who PM Julia Gillard labelled "irresponsible".

"[They] took a position that the Australian government was too spineless to take," Mr Burke said. "They are courageous Australians who believe in our sovereign laws and took desperate action to draw the line in the sand that our government is not prepared to draw.

"I don't believe they necessarily asked for Gillard's help; it's just costing us money now because the SM2 took them a thousand miles away and refused to bring them back. Sea Shepherd had no part to play in that and actually offered to pick them up from the SM2."

Mr Burke said the conservation society, which has three ships in Antarctica crewed by 90 people from 25 countries, was doing the government's work. "In Ecuador, we work together with that government. We stride side by side with the Ecuadorian navy and Galapagos National Park Service when it comes to tracking shark-finning poachers. [We] spend millions of dollars going to Antarctica every summer to uphold the laws that the Gillard government should be spending taxpayers' money to enforce. It's the whalers who are the eco-terrorists. So far this season, Japan has sent ships into Australian waters, taken our citizens out of Australia with neither passports nor Customs clearances, and sailed a functioning harpoon ship into Macquarie Island Australian territorial water, within four miles from shore."