A spokesman for Howard later told Reuters the four countries were key allies and united in ending whaling.

Japan, where whale meat is regarded as a delicacy, abandoned commercial whaling in 1986 in line with an international ban, but began a programme to hunt whales for "scientific research" the next year.

The meat ends up in restaurants.

Japanese media reported last month that Japan planned to expand its annual whale hunt to take two new species -- humpback whales and fin whales -- as well as nearly doubling its planned catch of minke whales.

The plan is to be submitted to the annual meeting of the International Whaling Commission (IWC) later this month.

Most of Japan's whale hunting takes place in Antarctic waters. Australia claims about 42 percent of Antarctica, while six other nations have laid claim to the rest, but not all countries around the world recognise these territories.

"Some people have said we should take action by force if necessary to keep them (Japan) out of the Antarctic. But bear in mind that Japan and many other countries do not recognise our claims in the Antarctic," Howard said.

"It's certainly not clear under international law that such behaviour by Australia would be correct. I think everybody would agree that the first thing we should try and do is bring about a change of attitude by Japan through diplomatic means."

Japan maintains that eating whale is an important part of its cultural heritage despite the protests of environmentalists determined to prevent the killing of the marine mammals, some species of which are endangered.

"We are very concerned about this. We find it hard to believe a cull of about 400 minke whales is scientific," Howard said.