TORONTO - "Avatar" director-turned-activist James Cameron says Alberta's tar sands are a "black eye" to his native country's image as an environmental leader.

The Canadian-born filmmaker says he wants to learn more about the controversial Athabasca Oil Sands Project after being contacted by indigenous groups who are concerned by its impact.

He questioned why Canada is spending billions on extracting crude oil instead of pursuing sustainable options.

"I think it's bad, I think it's the wrong solution for us to be doing greater and greater environmental damage pursuing a dead-end paradigm, which is fossil fuels, instead of spending those billions ... on building wind turbines," Cameron said Tuesday from his home in Los Angeles.

"Those same areas are a great wind belt and we could be generating ... wind energy out of the same place. Why aren't we doing that?"

Cameron, who was born in Kapuskasing, Ont., said he hopes to learn more about the issue this weekend when he meets with the Secretariat of the UN Permanent Forum on Indigenous Issues in New York.

He'll be there Saturday for a special screening of "Avatar," a futuristic tale in which humans battle a tribe of blue-skinned aliens over the precious resources of their planet, Pandora.

The Hollywood heavyweight has spent the past several months speaking out on various green issues, including a Brazilian dam project that he says threatens to displace tens of thousands of people.

His 3D epic is set for release on DVD and Blu-ray on Thursday, which is also Earth Day.

"It's kind of like 'Avatar' has become a portal for me into a kind of a world of social responsibility that I've kind of embraced. It's all part of the overall Avatar juggernaut," he says of his new role as eco-warrior.

"There's a danger of coming off as a kind of overnight expert but I have been studying this stuff for a long time, really for 20 years and I'm pretty up to speed on all the issues. I actually think that as an artist and as an activist I've got something to say and there's been a lot of people reaching out to me from various groups around the world to see if there's something I can do to help them in their causes.

"I'm trying to be somewhat judicious but certainly the fantasy that's shown in 'Avatar' is a reality for a lot of people around the world right now."

The outspoken Cameron also waded into controversial remarks attributed to "Avatar" actress Sigourney Weaver, who was quoted by Brazil's media saying that his ex-wife Kathryn Bigelow won the Oscar for best director because Cameron "didn't have breasts."

Cameron was more diplomatic Tuesday, insisting that Bigelow "did a great job" while suggesting that other factors were at play in the decision by the Academy of Motion Picture Arts & Sciences.

"I think she made a really good film and I couldn't be more pleased that she won as best director. I do think that there is an aspect of the way the Academy thinks, that it was an irresistible moment in history for them to anoint a woman finally. And really they're just dealing with the fact that it hasn't happened in the past. But I don't think that in any way diminishes Kathryn's accomplishment."

Cameron added that "Avatar"'s massive worldwide box office success was no small consolation.

"The audience has spoken. We made $2.7 billion. I think the court of public opinion finds in our favour."

"Avatar" also lost the best picture title to Bigelow's "The Hurt Locker," which took in an estimated $40 million worldwide.

Cameron's film stands to earn even more at the box office when it's re-released in August with six more minutes of computer-generated material.

Cameron says "several million dollars" are being spent to finish off scenes that were cut from the initial release. He says that will be part of a summer re-release for the 3D wonder, which will include another IMAX run.

The added scenes include Grace Augustine's schoolhouse and backstory and a hunting scene with a new creature known as the Sternbeast.

"The Sternbeast is a creature that was basically completely taken out of the film," Cameron says. "Not because we didn't like him, we loved the Sternbeast. But when we took out the Sternbeast hunt, the other times that we saw the Sternbeast we took out as well."

Other additions include an action sequence, a dramatic scene toward the end, and more of an infamous sex scene involving the Na'vi creatures.

"The sex scene in all its glory lasts an additional 12 seconds," Cameron said.

The big-screen return will be followed by the release of a four-disc DVD/Blu-ray box set, including lots of supplemental material.

But Cameron said a 3D home release will have to wait until more people buy 3D players for their homes.

The theatrical version of "Avatar" comes out on Blu-ray and DVD on Thursday and includes access to exclusive online content.