Its biggest star is British, and its director is white.

But "Concrete Cowboy," a critically acclaimed new film about at-risk black youths and horse owners in urban Philadelphia, offers a poignant message at a time of mass anti-racism protests in the United States, Idris Elba said Sunday.

The film follows a young black man (Caleb McLaughlin of "Stranger Things") who returns to an impoverished Philadelphia ghetto. He must choose between a life of crime and the close-knit horse-rearing community of his estranged father (Elba.)

"It was incredibly important to us... that we tell this story of the fork in the road that you can take as a young man in this country," Elba told the Toronto film festival when asked about US anti-black police violence in online talk.

"America didn't change overnight. These are issues that have been going on for a long time -- even where I'm from in England where there's a huge knife-crime problem," added the London-born star.

Director Ricky Staub stumbled upon the story, adapted from a novel, after spying a black cowboy riding a horse and a bright-red, decked-out buggy down the street outside his Philadelphia office window.

As characters in the film discuss, black cowboys were widespread but have been whitewashed out of history by Hollywood, and black urban riding clubs remain proud if little-known tradition.

Lee Daniels, best known for directing the Oscar-winning "Precious," admitted he was "shocked" to learn Staub was white and initially declined to produce the project.

"For a quick minute... you had to really think about it because I was out," he said. "And then I thought, I prayed, and I was... 'this is ridiculous, I'm in! This cat knows what he's doing.'

"And so then I opened myself up to him."

Reportedly shot for less than $10 million, the movie premiered in Toronto on Sunday.

Reviews praised an "astonishing street-level debut" for shining a light on a unique but fading subculture by using real-life "urban cowboys" as actors.

Elba himself had to overcome a severe horse allergy to film the movie. "I'm hoping that as a result... people look back at their communities and respect the role that communities play in young men's lives, young people's lives," said Elba, who played a Baltimore slum drug boss to massive acclaim in television's "The Wire."

"Because oftentimes it takes a village."

'Delicate'

Another film to use non-actors playing themselves -- "Nomadland," about America's fleet of ageing, itinerant van-dwellers, starring Frances McDormand -- screened in Toronto and scooped the Venice festival's top prize earlier this weekend.

Saoirse Ronan ("Lady Bird" and "Little Women") on Sunday discussed another potential Oscar contender that premiered in Toronto -- "Ammonite," in which she stars opposite Academy Award winner Kate Winslet.

The film was inspired by the real-life of British fossil-gathering palaeontologist Mary Anning (Winslet) and depicts a lesbian relationship with a grieving mother (Ronan) in 19th-century England.

The follow-up to director Francis Lee's "God's Own Country" moves at a gentle pace, but has received a number of rave reviews, with one Hollywood Reporter critic left unable to "think of a single aspect that could be improved upon."

"It takes so much time and care and patience to find the beauty in something and the strength of something -- and that is what these two women sort of do for one another," said Ronan, drawing parallels between searching for ammonite and love.

She added: "It's a very delicate movie."

Toronto, North America's biggest film festival, is taking place mainly online this year due to the coronavirus pandemic. It runs until September 20.