Paul Watson rejected calls by the Australian and Japanese governments to show restraint, the Australian Broadcasting Corp. reported.
"We're not going to restrain ourselves from protecting these whales and we're not going to restrain ourselves from upholding international conservation law," he said. "The Government has shown so much restraint over the years they have done absolutely nothing."
The Ady Gil, a lightweight 70-foot boat, was rammed Wednesday by a Japanese ship providing security for the whalers. The boat sank under tow Friday.
The Australian government said it has told Tokyo it might bring an international court challenge if negotiations on Japanese whaling stall, The Sydney Morning Herald reported.
The Japanese government says the country's annual whaling expedition to the Southern Ocean is for scientific purposes.