TOKYO- In an unusual move, US ambassador to Japan Caroline Kennedy has expressed deep concern over the traditional dolphin hunt in western Japan, where local fisherman corral dolphins in a secluded bay before killing many for meat.

The annual dolphin hunt currently underway in Taiji in western Japan has long been a source of controversy and was the topic of "The Cove," an Oscar-winning documentary.

"(I am) deeply concerned by inhumanness of drive hunt dolphin killing," Kennedy tweeted at the weekend, adding that the US government opposes drive hunt fishing.

Every year the fishermen of Taiji - a small fishing town in Japan's Wakayama prefecture - drive hundreds of dolphins into a cove, select some for sale to marine parks, release some back into the sea and kill the rest for meat.

Sea Shepherd, one of several animal protection groups that monitor fishermen in Taiji, said on Monday that more than 200 dolphins have been rounded up into the secluded bay by the shore off Taiji.

The organization is streaming live footage of Taiji's cove, showing fishermen on several fishing boats rounding up the dolphins inside the bay. The dolphins are cordoned off by large fishing nets.

Taiji shot to global infamy after the 2009 release of "The Cove," which was directed by former National Geographic photographer Louis Psihoyos. The film followed eco-activists who struggle with Japanese police and fishermen to gain access to the location of the hunt.

The movie met with fierce opposition in Japan from groups saying it was "anti-Japanese" and an affront to traditional culture.

Japan has long maintained that killing dolphins is not banned under any international treaty and that the animals are not endangered, adding that dolphins need to be culled to protect fishing grounds.