But officials in Tokyo said Japan would keep hunting the sea mammals despite international opposition.

Japan abandoned commercial whaling in 1986 in line with an international moratorium but the next year began to hunt whales for what it claimed was scientific research.

Environmental groups say it is commercial whaling in disguise - the meat ends up on store shelves and the tables of gourmet restaurants.

Tokyo authorities and fishery industry leaders also maintain that eating whale is an important part of the country's cultural heritage.

When Japan's five-ship whaling fleet arrived home Thursday after an Antarctic hunt that began last November and yielded 440 minke whales, the program was declared to have been concluded.

``The research program has been truly successful in having produced valuable information on the Antarctic ecosystem which will provide the basis for improving future research and comprehensive management of Antarctic marine resources,'' said Hiroshi Hatanaka, director-general of the Institute of Cetacean Research.

To obtain approval for its next research plan, the government will submit a proposal to the International Whaling Commission at its annual meeting in Ulsan, South Korea, this June.

But Japanese officials said the hunts will continue even if the IWC - split between pro- and anti-whaling camps - rejects their plan, details of which will not be public until June.

``Fundamentally, according to the international convention that established the IWC, any country that is part of it has the right to carry out whaling,'' said Hideki Moronoki, an official with the whaling division of Japan's Fisheries Agency.

``We intend to appeal for the legitimacy of our research.''

Japan blames whales for declining fish catches, saying the mammoth mammals consume such vast quantities of fish that they have contributed to a huge drop in fish landings.

It supports protection of endangered whales but argues that others - such as the minke - are numerous enough to be hunted within limits.

Japan and other pro-whaling nations have become increasingly frustrated by what they see as a growing anti-whaling slant to IWC meetings, especially after the 2004 meeting ended with a small but significant victory for countries that want to maintain the whaling ban.

Tokyo has even threatened to pull out of the IWC if a system to monitor whale catches and ensure nations stick to quotas under a return to large-scale whaling is not passed this year, a scheme that could spell an end to the whaling ban.