A black African woman has entered the race for Cannes's coveted Palme d'Or top prize for the first time in its 72-year history, with a moving ghost story about migrants dying at sea while trying to reach Europe.

Mati Diop, 36, grew up in France and belongs to a Senegalese artistic dynasty including her uncle, acclaimed director Djibril Diop Mambety, and her father, musician Wasis Diop.

She told AFP after the red-carpet premiere of "Atlantics" that it was while she was making a short film in Senegal a decade ago that she began to wrestle with the tragic push-and-pull factors leading Africans to flee the continent.

"I was spending time in Dakar at the time and was struck by the complex and sensitive realities of the phenomenon we called at the time 'illegal emigration'," she said.

"Once I had finished my (short) film, I felt I still had a lot of dimensions and issues to explore. I had the desire and the idea to tell the story of youth disappearing into the sea, through the perspective of a young woman."

She chose a Romeo and Juliet story of star-crossed young lovers, but with a supernatural twist.

The heroine of the film is Ada, growing up in a poor district of Dakar.

Although her parents have arranged her marriage to a wealthy young man, Ada has already fallen in love with Souleiman, a builder who's been cheated out of his salary by a corrupt developer.

He and a group of fellow workers decide their only future lies in Europe and set off in a motorised boat known as a pirogue for the Atlantic.

- 'Wait this long' -

News of the boat's sinking and the death of its passengers reaches home but Ada can't quite believe Souleiman is gone.

Suddenly her friends start seeing him everywhere around town and Ada receives mysterious text messages on her mobile, while more and more people come down with an inexplicable fever.

Their affliction, which also leads victims' irises to turn white, turns out to be a visitation of the souls of the dead, with Souleiman entering the body of a policeman.

The supernatural tale of love beyond death, which garnered strong reviews, drew comparisons to "Personal Shopper", the arthouse hit starring Kristen Stewart, and even the 1990 blockbuster "Ghost".

But the migrant crisis, in which nearly 2,300 people died trying to reach the shores of European countries last year according to the UN, adds political heft and moral urgency to the film.

Diop said that while the weight of the tragic situation was difficult to bear, she seized on the character of Ada, a young women who "wakes up to a new dimension of herself", as a ray of light.

Asked about her own role as a trailblazer at Cannes, Diop told reporters the news had "quite honestly made me sad at first because we had to wait this long."

Just four of the 21 directors vying for the Palme d'Or are women.

- 'So excited' -

She said she had had an "urgent need" to feel more represented on screen and see more people who look like her behind the camera, telling fresh stories.

"As a black woman I really missed black figures and black characters cruelly. And that's also why I made this film: I needed to see black people on screen -- huge, everywhere," she laughed.

"It's also something new. I can't believe when I go to see a Jordan Peele movie... I can't even believe what I'm feeling," she said, referring to the Oscar-winning African-American filmmaker behind "Get Out" and "Us".

"I'm so excited, I'm looking at how many black people are in the room -- I almost count them... it's a little hysterical."

Diop said Cannes as the world's biggest film festival had the power to help transform the industry by knocking down barriers for previously excluded groups.

"Hopefully it will be more and more common that black people are in front of characters of the same colour. Inshallah (God willing)," she said.