Stung by rare criticism from the US ambassador, the Japanese government has defended a controversial annual dolphin hunt as international criticism of the practice gathered pace.

A government spokesman said on Monday that dolphin fishing in western Japan, which has come under the spotlight in the wake of an Oscar-winning documentary, was carried out appropriately in accordance with the law.

"Dolphin fishing is a form of traditional fishing in our country," said chief cabinet secretary, Yoshihide Suga, responding to a news conference question about criticism from Caroline Kennedy, the US ambassador to Japan.

"We will explain Japan's position to the American side."

The hunt in the fishing village of Taiji in western Japan has come under international criticism and was the subject of the Academy award-winning 2009 film The Cove.

The fishermen in Taiji say the hunt is part of their village tradition and call foreign critics who eat other kinds of meat hypocritical.

Yoko Ono, the Japanese artist and peace activist, has added her voice to calls for an end to the practice, publishing an open letter to the people of Taiji on Monday in which she urged them to halt the cull for the "future of Japan."

"I understand how you must feel about the one-sidedness of the West to be angry at your traditional capture and slaughter of dolphins," she wrote.

Ono called on the locals in the area to "think of this situation from the point-of-view of the big picture" and claimed that the hunt was damaging the reputation of Japan and "will give an excuse for big countries and their children in China, India and Russia to speak ill of Japan."

She called on the people of Taiji to consider the future of Japan: "I am sure that it is not easy, but please consider the safety of the future of Japan, surrounded by many powerful countries which are always looking for the chance to weaken the power of our country. The future of Japan and its safety depends on many situations, but what you do with dolphins now can create a very bad relationship with the whole world."

Kennedy tweeted on Saturday: "Deeply concerned by inhumaneness of drive hunt dolphin killing." She said the US government opposed such fishing.

Drive hunt involves herding the dolphins into a cove, where they are trapped and later killed.

The hunt in the fishing village of Taiji in western Japan has come under international criticism and was the subject of the Academy award-winning 2009 film The Cove.

The fishermen in Taiji say the hunt is part of their village tradition and call foreign critics who eat other kinds of meat hypocritical.