TOKYO - THE Japanese whaling company whose ship came under attack this week from militant environmentalists is preparing to sue them, a report said on Wednesday.

Activists from the Sea Shepherd Conservation Society on Monday hurled stink bombs on the Japanese whaling ship, slightly injuring three crew and coast guard members onboard, according to Japan.

Kyodo Senpaku Kaisha Ltd is studying video footage of the activists to identify them with a view to suing them, the Japan Broadcasting Corporation (NHK) said.

The company declined to comment on the report, which did not cite its sources or say where legal proceedings would be launched.

Sea Shepherd mocked the 'gasp of horror' over Monday's incident, saying it threw rotten butter that does not hurt anyone.

Japanese officials described the substance as butyric acid, which is stinging to the eyes.

'There is no industry on earth as horrifically violent as whaling,' a Sea Shepherd statement said. Whales 'may take up to 40 minutes to die as they drown in a mixture of salt water and their own blood.'

'Yet some people get upset because these same people now have smelly decks and can't continue their foul sadistic work,' it said.

Kyodo Senpaku Kaisha is a private Japanese company that is under government contract to carry out the controversial whaling expedition.

Japan kills up to 1,000 whales a year using a loophole in a 1986 global moratorium on whaling that allows 'lethal research' on the giant mammals.

Japan, which says whaling is a tradition, makes no secret that the meat ends up on dinner plates and accuses Western nations of cultural insensitivity.

Australia, where whale-watching is a major industry, has stepped up anti-whaling efforts under new Prime Minister Kevin Rudd.

Japan has said it will raise the Sea Shepherd attack when members of the International Whaling Commission, which is deeply divided between pro- and anti-whaling forces, holds an informal three-day meeting in London starting Thursday.

Tokyo earlier summoned ambassadors from Australia, where the Sea Shepherd boat last docked, and The Netherlands, where the vessel is registered.