Activists protesting against Japan's indigenous dolphin hunting held a rally in Tokyo Friday, calling on officials to stop sales of the marine mammals to aquariums and as meat.

Some two dozen campaigners, mostly Japanese, congregated in front of the Fisheries Agency with banners and pictures, urging the government to ban dolphin catching.

"Most Japanese people do not know about dolphin hunting," said Noriko Ikeda, who organised the rally and a member of Action for Marine Mammals.

"The government has argued the practise is part of the Japanese tradition and food culture.

"But reality is that it is extremely rare to find Japanese people who wish to eat dolphins. The real problem is that hunt is driven by demand for live dolphins among aquariums to put on dolphin shows," she said.

The US ambassador to Japan Caroline Kennedy recently tweeted her concern at the "inhumaneness" of a Japanese village's traditional dolphin hunt.

"Deeply concerned by inhumaneness of drive hunt dolphin killing. USG (US Government) opposes drive hunt fisheries," she said in an online post.

Every year the fishermen of Taiji in western Japan corral hundreds of dolphins in a secluded bay, select a few dozen for sale to aquariums and marine parks and kill the rest for meat.

Activists from the international militant environmental group Sea Shepherd have streamed live footage of the dolphin capture in Taiji, which drew worldwide attention in 2010 when it became the subject of the Academy Award-winning documentary "The Cove".

Defenders of the hunt say it is a tradition and point out that the animals it targets are not endangered, a position echoed by the Japanese government.

They say Western objections are hypocritical and ignore the vastly larger number of cows, pigs and sheep butchered to satisfy demand elsewhere.

The Japanese activists who gathered Friday said dolphin hunting was tarnishing Japan's reputation as Tokyo prepares to host the 2020 summer Olympic Games.