Sea Shepherd protest ships rammed by whalers

Crews aboard an anti-whaling protest ship in the Southern Ocean have escaped injury but are struggling to mend "significant damage" to their vessel after it was rammed by Japanese whalers.

Two protest ships belonging to anti-whaling organisation Sea Shepherd were hit by Japanese whale-processing factory ship, Nisshin Maru, this afternoon.

The boats, Steve Irwin and Bob Barker, have been following the vessel in the Southern Ocean to try to prevent the slaughter of whales.

Speaking from onboard Steve Irwin, Captain Paul Watson said the crews and boats were targeted in an aggressive attack - the first of its kind from the Japanese vessel.

"The Nisshin Maru came in to push us away from blocking their attempts to refuel at the Sun Laurel," he said.

The Japanese vessel hit the Steve Irwin twice and then hit Bob Barker several times, pushing it into the Sun Laurel, which was also damaged in the collisions.

"This is a massive vessel. When it hit the Bob Barker it was like a tank hitting a car; it just rolled right over it. I thought they were literally going to crush the Bob Barker and sink it."

"Nobody's been injured amazingly enough, because while they were hitting the boats they were also throwing stun grenades at the crew and hitting them with water cannons."

There are 34 people on the Bob Barker and 42 on the Steve Irwin.

Bob Barker was initially taking on water in the engine room, but crews had stopped the leak and were trying to restore power to the ship, said Mr Watson.

Lifeboats aboard the Sun Laurel had also been damaged, Mr Watson said.

The fuel ship was heading north and the two protest boats would continue to hold their positions.

"We follow the whaling vessels wherever they go to make sure they don't kill any whales."