Two anti-whaling activists, one an Australian, were feared missing in Antarctic waters after a clash with a Japanese whaling fleet.
A search for the two men was under way after the anti-whaling group Sea Shepherd confronted Japanese whaling vessels in the Ross Sea.
International director of Sea Shepherd, Jonny Vasic, said anti-whaling activists from two ships had used high speed inflatables to try to disrupt the operations of the whaling fleet.
But a mayday message was issued after radio contact was lost with two activists in an inflatable.
One of the men was an Australian from Perth and the other an American from New York, said Captain Paul Watson, aboard the Sea Shepherd vessel Farley Mowat.
"I am confident we should be able to find them. They are dressed for the conditions," he said.
The activists would have been wearing survival suits.