Japanese Prime Minister Yukio Hatoyama told his Australian counterpart Kevin Rudd Tuesday to make an "appropriate" response to anti-whaling activists' interference with Japan's annual hunt, dpa reported.
Last month, a Japanese whaling fleet left to hunt in waters south of Australia.
Hatoyama said any illegal acts by the US-based Sea Shepherd Conservation Society to block the fleet and its crew would threaten its safety. He also said Japan's whaling programme is internationally authorized.
Rudd threatened legal action against Japan over the whaling if a diplomatic resolution proves difficult, news reports said.
The two leaders, however, agreed to continue their dialogue to resolve the issue.