Environmentalists chasing a Japanese whaling fleet off Antarctica threw "stink" bombs and dye at one of the vessels, Japanese authorities and the Sea Shepherd Conservation Society said.

The two vessels collided during the incident, but both sustained only minor damage limited mainly to their paintwork, said Paul Watson, founder of the envirionmental group.

The US-based group said the Japanese ship, the Kaiko Maru, was spotted by its vessel the Steve Irwin north of Mawson Peninsula.

The stink bombs were made of biodegradable, harmless materials including rancid butter, chemically known as butyric acid, Watson said, adding that the Japanese ship appeared to have been taken by surprise.

"Butyric acid is the technical name for rotten butter. Beer is more acidic than this stuff," he said from the Steve Irwin.

The Japanese Fisheries Agency said no one was hurt during the incident which lasted about three hours, Kyodo news agency reported.

Japan's whaling fleet is in the Antarctic for an annual hunt. Despite an international ban on whaling, Japan justifies the hunt on the grounds this whaling is for "scientific" purposes.

Much of the meat ends up on supermarket shelves.