Japan's peak whaling body has launched a new campaign to promote whale meat as a nutritious food that enhances physical strength and reduces fatigue.

With about 5,000 tonnes of whale meat sitting unwanted in freezers around Japan, the country's Institute for Cetacean Research has decided to launch a new campaign to promote the by-product of its so-called scientific whaling program.

Once popular in school lunches, younger generations of Japanese rarely, if ever, eat whale.

But the institute hopes to revive flagging interest by advertising whale meat as a great source of balenine - a substance believed to enhance energy and physical health.

Japanese media are reporting the campaign also involves selling whale meat to defence forces to help boost their strength.

As part of the campaign, about 7,000 brochures will be distributed that feature recipes such as whale meat sashimi and whale cooked with Chinese chives.