Anti-whaling activists threw rotten butter at a Japanese whaling ship today in an attempt to sabotage their operations.
Protesters on a boat operated by the Sea Shepherd group said they were trying to make the decks too slippy to work on.
Japanese officials said at least three crew members were slightly injured on the Nisshin Maru whaling ship, which is conducting what Japan calls a research whaling programme in the Antarctic.
Sea Shepherd and other anti-whaling protesters have continually harassed the Japanese whaling fleet in an effort to interfere with the hunt. Japan kills about 1,000 whales every year under an internationally sanctioned research programme.
Japan has accused the activists of terrorist tactics, but Sea Shepherd called on Japan to stop its hunt in a statement issued after the confrontation.
The group said it threw more than two dozen bottles of rotten butter onto the Japanese ship, as well as packets with an unspecified slippery chemical onto the deck to interfere with the butchering of whale carcasses.
"I guess we can call this non-violent chemical warfare," said Sea Shepherd leader Paul Watson in the statement.
Australian Foreign Minister Stephen Smith, a critic of Japan's whale hunt, deplored the attack and urged all parties in Antarctic waters to exercise restraint.
"I absolutely condemn actions by crew members of any vessel that cause injury - or have the potential to cause injury - to anyone on the high seas," he said.
The confrontation coincided with a conference in Japan aimed at persuading several African and Asian countries to support Tokyo's push to overturn a 1986 international ban on commercial whaling.
Japan is waging a battle in the IWC for votes in support of its position. Tokyo denies the allegation by anti-whaling nations that it tries to buy IWC votes with aid. The group was also to be treated in coming days to trips to Ayukawa and Taiji, two Japanese whaling ports.