Greenpeace vessel Arctic Sunrise was damaged in the collision but spokesman Shane Rattenbury told AFP by satellite phone that the ship would be able to continue its pursuit of the Japanese whaling fleet.

"Despite the fact that we took some damage (Sunday), it was all above the deckline. There's no leaks in the ship. It's quite seaworthy so we're determined to stay on for as long as we can," he said.

Greenpeace and the Japanese whaling authority have accused each other of deliberately causing the collision.

The Arctic Sunrise and another Greenpeace ship, Esperanza, have been shadowing the Japanese whaling fleet since December 21, attempting to disrupt the killing of whales.

The International Whaling Commission imposed a moratorium on commercial whaling in 1986 but Japan has continued hunting for what it calls scientific research -- a claim rejected by critics.

The Japanese Institute of Cetacean Research (ICR) said the Greenpeace vessel "deliberately rammed the Japanese research vessel, the Nisshin-Maru, in the Antarctic while it was attempting to transfer cargo".

ICR director-general Hiroshi Hatanaka called on Greenpeace and another anti-whaling group, Sea Shepherd, to "stop at once their dangerous and criminal actions."

Rattenbury, however, said the Japanese ship had turned a full circle behind a resupply vessel to head directly towards the Arctic Sunrise.

"It was a very deliberate incident because there was absolutely no need for them to have come round the vessel. They really had to seek us out, to come around the resupply vessel and strike us," he said.

"The other thing that highlighted the premeditated nature of it was that after we were struck they turned the water cannon into our bridge as they went past so we took a direct blow from the water cannon as well."

Greenpeace was "examining its options" over the possibility of taking legal action against the Japanese captain, Rattenbury said.

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