Anti-whaling activists are prepared to end aggressive protests against Japan's scientific whale cull if Australia or New Zealand agree to challenge the hunt in an international court, protesters said yesterday.

The Sea Shepherd Conservation Society, blamed for collisions with the Japanese Antarctic whaling fleet in recent years, as well as high-seas boardings and stink bomb attacks, said it was willing to "back off" for a season if either country acted.

"Take them to court, and if that fails, if the Japanese refuse to appear, if they refuse to abide by any legal decision, Sea Shepherd could then return with a much more aggressive approach," captain Paul Watson said in a statement.