The first Australian Customs plane sent to observe protesters and Japanese whalers has been spotted in Antarctic waters.
The Bob Barker ship of anti-whaling group Sea Shepherd reported seeing the plane hover overhead for about eight minutes just after 9am Sunday (AEDT).
Ship captain Peter Hammarstedt says no contact was made with the Australian Customs aircraft.
The plane spotting comes after Sea Shepherd Australia chairman and former federal Greens leader Bob Brown urged the Australian government to police the whaling activity after obtaining footage of dead whales on Japanese vessels.
The Abbott government made an election promise to send a customs vessel to monitor Japanese whalers in Antarctica, but after the election promised only a plane to observe protesters and whalers in the Southern Ocean.
Sea Shepherd Australia has three ships and about 100 crew – half of whom are Australian – from 21 countries in Antarctic waters to confront Japanese hunting in the Southern Ocean Whale Sanctuary, south of Australia, where commercial whaling is banned.
On Friday, a Japanese whaling ship that was pursuing the anti-whaling activists stopped just outside Australian waters after an apparent intervention by the Australian government.