WASHINGTON ? Avatar director James Cameron vowed Friday to fight on for the indigenous people of the Amazon after a Brazilian court overturned a ruling that would have halted construction of a huge dam that would flood tribal lands.

"We are disappointed but we knew this would be a long battle," Cameron told Agence France-Presse by phone during a brief visit to Washington.

"If Brazil lets me back in, I would love to come back down and work with the indigenous people I met" during several visits to the vast South American country after the release of Avatar, Cameron said.

"But I want to go back as a film-maker, not a sign-waver. I want to film the culture of the Kayapo Indians and let the world see how they live in harmony with the forest," he said, evoking strong parallels with Avatar.

The blockbuster movie tells the story of the peaceful Na'Vi people who live in harmony with nature on the planet Pandora and are forced to wage a bloody fight against strip-miners from Earth who have no compunctions about destroying the Na'Vi culture to get their hands on a precious mineral, unobtainium.

"Avatar was based on real but abstract stories. It came out of articles in National Geographic and documentaries on TV.

"But after meeting the indigenous people of the Amazon with whom we communicated very clearly and emotionally, it's real for me. And it's personal," Cameron said.

After he had finished filming Avatar, the veteran film director and self-avowed environmentalist traveled several times to Brazil on fact-finding missions to "drill down and study the tectonic interface between progress pushing up against the natural world and bulldozing it out of the way."

"It's happening now and it's a reality for these people" in the Amazon, he said, adding that his visits to Brazil had helped to shine an international spotlight on the fight being waged by Amazon communities to preserve their forest and river communities.

"Through our visits, we were able to get the story on the front page of newspapers in the US, and I don't believe that the powers that be in Brazil really expected that kind of media scrutiny of a process they had tried to keep out of the public eye," Cameron said.