Australia released grisly surveillance pictures of the slain carcasses of two whales being hauled aboard a ship, stepping up its campaign Thursday against Japanese whaling in Antarctic waters.

Environment Minister Peter Garrett said the "distressing" pictures would help build global opposition to whaling.

"It is explicitly clear from these images that this is the indiscriminate killing of whales, where you have a whale and its calf killed in this way," Garrett told reporters in Sydney.

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The Institute of Cetacean Research, the Japanese government-affiliated organization that oversees the hunt, posted a statement on its Web site headlined: "Australian Customs Photos Mislead the Public."

"The Government of Australia photographs and the media reports have created a dangerous emotional propaganda that could cause serious damage to the relationship between our two countries," institute director Minoru Morimoto said in the statement.

It was not immediately clear when the whales were photographed being hauled by their tails aboard the harpoon ship Yushin Maru 2.

The images were taken by an Australian customs ship that has tracked the Japanese fleet in the Antarctic Ocean for the past month gathering evidence for a diplomatic and legal battle against whaling.

Hideki Moronuki, chief of the Japanese Fishing Agency's whaling section, denied that one of the photographs depicted a calf.

"The fleet is engaged in random sampling, which means they are taking both large and small whales. This is not a parent and calf," Moronuki said.

He criticized the Australian ship for coming too close to the whaler to take the photographs, calling it "the sort of dangerous action that Sea Shepherd and Greenpeace have engaged in," referring to conservation groups that have harassed the whalers.

Japan temporarily halted its hunt in mid-January after sea confrontations with both Greenpeace and Sea Shepherd.

Japan has staunchly defended its annual killing of more than 1,000 whales, conducted under a clause in International Whaling Commission rules that allows whales to be killed for scientific purposes.

Critics dismiss the Japanese program as a disguise for commercial whaling, which has been banned by the commission since 1986.

Australian Home Affairs Minister Bob Debus said the images released Thursday were evidence that could be used against Japan to halt the annual slaughter.

"They will help us to back up the Australian government's argument in an international court case, the details of which are still to be worked out, to suggest that whaling should be stopped," Debus told reporters.

Australia has yet to decide who to prosecute and in what court, he said.