Anti-whaling group says boards Japanese ship

SYDNEY (Reuters) - An anti-whaling protester riding a jet ski boarded a Japanese whaling ship in the Southern Ocean on Monday in an attempt to make a citizen's arrest of the skipper, an environmental group said.

New Zealander Pete Bethune, who's boat "Ady Gil" sank after a collision with a Japanese whaler in early February, climbed on to the Shonan Maru 2 before sunrise, said the group, the Sea Shepherd Conservation Society.

"Captain Bethune boarded a Japanese whaling fleet security ship at high speed in total darkness, breached the spikes and anti-boarding nets and is presently onboard," Sea Shepherd head Captain Paul Watson said in a statement.

When two Sea Shepherd activists boarded a Japanese whaler in 2008 they were held until an Australian fisheries patrol boat agreed to intervene and pick them up.

Clashes between Japanese whalers and the Sea Shepherd Conservation Society have become an annual feature of the hunt for whales in Antarctic waters.

The Sea Shepherd's "Steve Irwin" ship has been chasing the Japanese whaling fleet in recent weeks trying to stop the hunt.

Australia last month pressed Japan to ensure its ships operate more safely after the activists accused whalers of sinking the Ady Gil powerboat.

Commercial whaling was banned under a 1986 international treaty, but Japan, which considers whaling a cultural tradition, deflects criticism by saying it culls whales for research.

Australia opposes the Japanese whal hunt, but the two countries have agreed not to let the issue hurt bilateral ties.

(Reporting by Michael Perry; Editing by Nick Macfie)