Japan has rebuffed public criticism of its whale hunting programme by the Prime Minister of New Zealand, Helen Clark.

Ms Clark said she did not believe Japan's whaling was for scientific purposes and that she supported the efforts of Greenpeace, the environmental group, to stop Japanese whaling ships.

But in a letter to Ms Clark, Japan's Agriculture and Fisheries Minister questioned the prudence of a prime minister in supporting a group like Greenpeace.

Annual hunt

Five Japanese whaling ships are currently at sea in the Antarctic hunting minke whales.

The annual catch, this year expected to be 400, was agreed with the International Whaling Commission in 1987.

The whales caught are officially used for scientific research.

Greenpeace has targeted this year's hunt by trying to disrupt the ships' mission.

The environmental group says Japan should carry out research on whales by watching them, not killing them.

Environmental concerns

New Zealand's Prime Minister, Helen Clark, has supported that view and criticised Japan for, allegedly, promising international aid to countries which would back its whaling programme.

She said New Zealand was concerned about the effects of whaling on the environment on the South Pacific.

Japan's Agriculture and Fisheries Minister, Tokuichiro Tanazawa, hit back in a personal letter to Ms Clark.

In it, he questioned the wisdom of a Prime Minister who expresses support for a pressure group which he said is known to force its beliefs on others by means of violent actions.

Mr Tanazawa said he hoped that the public image of New Zealand would not be damaged by the incident.

Whale meat used to be part of everyday meals in Japan, but these days it is a rare and expensive luxury - in fact, few people say they would miss it if it disappeared from their tables.

Nevertheless, the government staunchly protects its rights to catch minke whales and most of the whales caught do eventually end up for sale as food.