TOKYO?The Tokyo International Film Festival opened Saturday with a debut screening of a US-made documentary about a traditional dolphin hunt in Japan a contentious inclusion at the week-long gala.

Since last year the festival has taken on the theme of the environment, with guest overseas movie stars, filmmakers and other dignitaries walking along a ceremonial green carpet instead of the usual red.

Stars attending the opening ceremony of the 22nd edition of TIFF, which runs through to October 25, include American actress Sigourney Weaver and actor Sam Worthington, star of James Cameron's new film "AVATAR Special Presentation".

The hard-hitting "The Cove", a late inclusion at the festival, will be shown for the first time publicly in Japan, with some saying it casts Japanese tradition in a negative light.

It focuses on the annual dolphin hunt in the coastal town of Taiji, a long practice for local fishermen but condemned internationally by animal rights activists for being cruel.

The film shows angry confrontations between residents and the lead activist, Ric O'Barry, who in the 1960s trained dolphins for the US hit television show "Flipper" but now argues the animals should be free to roam the oceans.

The film has won numerous international prizes, including the Sundance Festival's audience award.

TIFF has aspired to be the top festival in Asia for international films with the same prestige as Cannes, Venice or Berlin, although it faces tough competition from rivals in Bangkok and Busan, South Korea.

In addition to "The Cove" and "AVATAR Special Presentation", other special screenings include "Drag Me to Hell", directed by Sam Raimi, as well as the Japanese re-make of the 2004 Oscar-winning "Sideways".

Fifteen movies ranging in theme and style will compete for the Tokyo Sakura Grand Prix, the top prize.

New premier Yukio Hatoyama, sporting a green bow tie in a nod to the environmental theme, and his wife Miyuki were among those who attended the opening of the gala.