Australian Greens Leader Bob Brown has called on the government to investigate a report today that Japanese whalers have breached the Antarctic Treaty by refuelling in a prohibited area.

"Sea Shepherd has just reported to Australian Customs that the Japanese whaling fleet was seen refuelling in Antarctic waters just a short distance away from a major penguin colony, which is a breach of the Antarctic Treaty," Senator Brown said.

"The Australian Government should investigate this report by sending the Oceanic Viking down to our territorial waters to ensure international agreements are being upheld by the whalers.

"I have written to the Minister for the Environment, Peter Garrett, to ensure he is aware of this extremely concerning action by the Japanese whalers, but I don't expect him to take any action," Senator Brown said.

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