Japan has summoned the ambassadors from Australia and The Netherlands over an incident in which environmentalists threw acid onto a Japanese whaling ship in the Southern Ocean, injuring at least three people.

The foreign ministry in Tokyo says the ambassadors have been urged to get their governments to take measures to prevent further violence.

Anti-whaling protestors have confirmed they threw more than 20 bottles and packets of substances onto the ship.

But the Japanese government says the protestors hurled butyric acid, which can potentially burn the skin and eyes.

Australia's foreign affairs minister, Stephen Smith, has condemned the attack by the militant Sea Shepherd group, which has vowed to stop Japan's whaling by force if necessary.

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