The government has called on the Netherlands to take effective action to prevent the Sea Shepherd Conservation Society from interfering with Japanese whaling ships, fisheries minister Yoshimasa Hayashi said Tuesday.

The move came after a Dutch-registered Sea Shepherd vessel approached unusually close last Friday to two Japanese ships in the Antarctic Ocean in the group's first act of sabotage against this season's hunt.

Hayashi criticized the hardline antiwhaling group, calling what it did "an unforgivable act that threatens legitimate whaling activities and the lives of crew members."

In December, a U.S. appeals court issued an order banning Sea Shepherd from attacking the Japanese government-funded whaling fleet in the Antarctic Ocean or from approaching the fleet on the open sea.

In the face of the latest attack, the Tokyo-based Institute of Cetacean Research, which has led the research whaling, will file a complaint against the conservationist group.