A fleet of three whaling vessels returned to port in Japan on Friday with the carcasses of 333 minke whales harpooned in the Antarctic Ocean.

The fleet - the 8,145-ton Nisshin Maru, the only whaling factory ship in the world, and two catcher vessels - was greeted by relatives of the crew in the city of Shimonoseki, a traditional whaling community in south-west Japan.

The Fisheries Agency issued a statement in which it confirmed that the fleet had carried out its four-month mission to conduct "research for the purpose of studying the ecological system in the Antarctic Ocean".

Activists dispute that claim and say the annual hunt is thinly disguised commercial whaling because the whale meat is later sold in supermarkets or served up in school dinners.