The pictures, plastered over front pages and shown on television here Thursday, were taken from an Australian customs vessel tracking the whalers to gather evidence for possible legal action to stop the annual slaughter.

"I guess when I saw the photos I just felt a bit of a sick feeling as well as a sense of sadness," Environment Minister Peter Garrett told Nine Network television.

"It's very disappointing. It's distressing when you think that it can take up to 15 minutes after a harpoon actually hits a whale for the whale to die.

"It's even sadder when you consider there's a calf involved."

A gaping wound visible on the side of the calf as it is hauled up a blood-slicked slipway into the boat was caused by an explosive-packed harpoon, the Daily Telegraph said.

The paper quoted scientists as saying that the small minke whale was probably less than 12 months old and still suckling.

Australia has taken a leading role in opposing Japan's use of a loophole in an international moratorium on whaling to kill the giants of the oceans in the name of research. The meat is then sold in supermarkets and restaurants.

"Images like this, that have been captured in the past, have been very powerful forces in building up global and world opinion on this issue," Garrett said.

"This isn't about science. It isn't about research ... they're calling it science but really it's killing whales."

Canberra was determined to pursue its campaign against whaling and would appoint a special envoy to talk with the Japanese on the issue while considering international legal action, Garrett said.

"We have to consider the options on legal action because it's a big step to be taken. But we're going to look at that very closely and some of the images that have been captured will inform that decision," he said.

"We're in for the long haul and we'll continue the surveillance activities as long as necessary."

Japan resumed its annual whale hunt last week after it was disrupted in mid-January by anti-whaling protests, including the boarding of one of its ships by two activists from the Sea Shepherd Conservation Society.

But low fuel forced boats from Sea Shepherd and Greenpeace to return to port to refuel and only the customs vessel, the Oceanic Viking, is now tracking the whalers.

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