The institute which has been licensed by the Japanese government to carry out research on whales, the Institute of Cetacean Research, has been providing whale meat for school lunches.

The Kyodo News service has reported the practice started in 2009.

Japan, whose stocks of whale meat have risen to about 4,000 tons, has been trying to increase consumption by subsidizing the cost of the meat to participating schools.

On school lunches the meat sells for one-third the market price.

Whale meat, which often appeared in school lunches in the 1970s, had disappeared from menus until the meat began to be marketed as a byproduct of whaling research.

Other countries have opposed Japanese whaling, saying its so-called research program is a disguised form of commercial whaling.

Japan's whale fleet operates primarily in the Antarctic where it hunts endangered whales protected by international law.

The International Whaling Commission has called on the international community to investigate Japan's self-set annual whaling quota.

Under the law, which the commission accuses of being flawed, every country in the world is prohibited from commercial whaling, but can set its own quota of whales captured for research and can sell the 'excess' meat on the open market.

Japan has set itself a quota of two to three hundred whales, which it captures in the name of research, according to the government.