Environmental activist group Sea Shepherd has accused Japan of funding the killing of whales with money donated to victims of the tsunami-earthquake.
Japan's whaling fleet has again set sail for the country's annual hunt in Antarctica, with security measures beefed up amid international protests.
Sea Shepherd is preparing to confront the whalers in the Southern Ocean for the eighth year, in what is expected to be one of its most intense campaigns yet.
Sea Shepherd captain Paul Watson said it looked like the Japanese fleet had two security vessels with security and coast guard personnel aboard.
"We are hoping to deter their operations," he said.
"I assume the security vessels will try and dislodge us. I am assuming there will be some difficult confrontations," he said on Wednesday.
"That is one of the reasons I asked Australia to send a vessel down to keep the peace, but they refused."
An extra $A28 million ($36.84 million) that Japan had given to the campaign was likely behind the beefed-up security, he said.
"That money did come from the earthquake relief fund.
"I think that it's totally disgraceful. People from around the world sending money to help the victims of the tsunami-earthquake were not expecting their money to be used to fund killing whales in the Southern Ocean."
Three ships from the Sea Shepherd fleet will set sail in about eight days.
In October, Australia and New Zealand renewed their demands that Japan abandon its plan to return to the Antarctic Ocean.
Foreign Minister Murray McCully said at the time the plan was "entirely disrespectful of the strong concerns expressed by Australian and New Zealand people, for whom the Southern Ocean is our neighbourhood".
NZN