Aretha Franklin 'lost' film Amazing Grace gets first trailer and it'll make you dance

But the soul singer is concerned about legal issues to do with the film's release

Aretha Franklin is concerned about legal issues relating to the Amazing Grace documentary

Never-before-seen footage of soul legend Aretha Franklin recording the biggest-selling album of her career is about to be shown in public for the first time.

Late director Sydney Pollack filmed behind-the-scenes at the "Respect" singer's 1972 gospel concert inside a Los Angeles church, a show which went on to become Amazing Grace.

More than 43 years later, the resulting documentary of the same name has its first trailer and is set to premiere at the Toronto International Film Festival next month.

Scenes of fans, including Rolling Stones frontman Mick Jagger, dancing to Franklin's awesome vocals are sure to raise spirits and get everybody in the mood for a boogie, but the 73-year-old has alleged that there are legal issues with the release.

"It isn't that I'm not happy about the film, because I love the film itself," she said, according to the Detroit Free Press. "It's just that - well, legally, I really should just not talk about it, because there are problems."

Franklin added that if certain things are not changed, an injunction could still be issued.

She has already sued producer Alan Elliott once, in 2011, and they settled out of court. Elliott now claims to have found her contract with Warner Bros from 1972 which he thinks clears the path for the project to go ahead. Technical issues meant Pollack's many hours of footage could not be edited into a film at the time.

Franklin's lawyer Arnold Reed has described the documentary as "a case of individuals hell-bent on exploiting the name and likeness of a world renowned musical icon, at all costs".

Elliott is showing no signs of backing down, however, describing the concert as Franklin's "crowning achievement" and "the most important document of American popular music ever filmed".