Japanese whalers released new video and photographs on Monday (February 25) which they said show anti-whaling group Sea Shepherd's ramming vessel their harpoon ship in order to hamper fuelling in the Southern Ocean.

The Institute of Cetacean Research (ICR), a Japanese group that runs the whaling programme, said in a release that Sea Shepherd's "Bob Baker" vessel collided with its "Nisshin Maru" and fuel tanker ship at least five times starting from noon on Monday.

The activists had been attempting to prevent refuelling between the tanker and the Japanese whaling fleet's 8,000-tonne factory when the collision occurred.

No Japanese crew members were injured, ICR said, and the damage to the ships was yet unknown, the release said.

Monday's clash followed a similar incident last week in which both sides blamed each other for colliding and damaging their own vessels.

The Sea Shepherd has clashed frequently with the Japanese fleet over nine whaling seasons during the southern hemisphere summer.

Japan introduced scientific whaling to skirt a commercial whaling ban under a 1986 moratorium. It argues it has a right to monitor the whales' impact on its fishing industry.