TOKYO, JAPAN - JAPAN on Tuesday lashed out at conservation activists who attacked its whaling fleet and said it would raise the incident at this week's meeting of the deadlocked International Whaling Commission.

The Sea Shepherd group, which has vowed to use all means necessary to stop the killing of whales, threw acid and other projectiles at the whalers' main ship on Monday, lightly injuring three crew and coast guard members.

Japan summoned the ambassadors of Australia, the main opponent of its whaling and where the Sea Shepherd boat last docked, and of The Netherlands, where the US-based environmental group's vessel is registered.

'It's not permissable to use violence to try to force through one's opinion,' Foreign Minister Masahiko Komura told reporters.

Transport Minister Tetsuzo Fuyushiba added: 'We can't forgive this. We need to make due protests.' Japan will seek to raise the issue when members of the International Whaling Commission (IWC) start an informal three-day meeting in London on Thursday, said Mr Masatoshi Wakabayashi, the agriculture and fisheries minister.

The London meeting was arranged by the US commissioner to the IWC, Mr William Hogarth, in a bid to break a bitter deadlock between its pro- and anti-whaling groups.

Mr Hogarth, the current IWC chairman, helped persuade Japan last year as a goodwill gesture to suspend its plans to kill humpback whales for the first time in four decades.

'We will take up this case in which the safety of our research was interrupted,' Mr Wakabayashi said.

Japan, which says whaling is part of its culture, kills up to 1,000 whales a year using a loophole in a 1986 global moratorium that allows 'lethal research' on the giant mammals. The meat then goes onto dinner plates.

Australia, where whale-watching is a major industry, has stepped up anti-whaling efforts under new Prime Minister Kevin Rudd, who sent a customs ship to monitor the hunt.

Australia condemned the latest attack by Sea Shepherd and appealed for restraint from both sides. -- AFP