Tokyo - Japan's whaling fleet failed to achieve its target but still returned to port with the meat of 680 whales on board.

The fleet's mothership, the Nishin Maru, returned Tuesday to its home port of Shimonoseki in south-western Japan after the close of the Antarctic hunting season, media reports said Wednesday.

The fleet had aimed to kill 900 minke and other whales, but Japan's Fisheries Agency said the militant, US-based environmental group Sea Shepherd hampered the hunt.

A global whaling moratorium was imposed in 1986, but Japan conducts its annual hunt under a rule by the International Whaling Commission that allows whaling for scientific purposes.

Japan said it is the only country that can furnish useful data on the management of the whale population because of its long-term research programme, but critics accused Japan of using the rule as a loophole to conduct hunts for commercial purposes.

Shigetoshi Nishiwaki, the research leader of Japan's whaling fleet, sharply criticized what he called Sea Shepherd's aggressive tactics.

A ship belonging the group collided in February with a vessel from the Japanese fleet. No one was hurt, but Sea Shepherd activists tried to take a whaling ship's propeller out of commission and threw bottles of butyric acid at the fleet's vessels.

As a result, the Japanese fleet was unable to operate on 16 days of the 100-day Antarctic hunting season, Nishiwaki said. (dpa)