The Antarctic whaling conflict appears to have taken a dangerous turn, with claims Japanese ships attempted to sabotage Sea Shepherd vessels in the ice-strewn Ross Sea.

Ships from the two sides collided on Sunday and Japanese harpoon ships are said to have tried repeatedly to foul the propellers of the acivists' ships with steel cables and rope.

Despite the clashes, Sea Shepherd's Peter Hammarstedt said the activists were still in contact with the fleeing Japanese factory ship, Nisshin Maru.

Mr Hammarstedt said his ship Bob Barker and the Steve Irwin were following the Nisshin Maru for the eighth day, preventing it from whaling, at a distance of about two nautical miles when a concerted attack began.