Kevin Costner and Sienna Miller premiered their Western "Horizon: An American Saga" at the festival
Kevin Costner and Sienna Miller premiered their Western "Horizon: An American Saga" at the festival AFP

A Donald Trump biopic looked set to trigger huge controversy in Cannes on Monday as the world-famous film festival reached its midway point.

"The Apprentice", a look at Trump's formative years, will have an evening premiere on the French Cote d'Azur, where the word from critics is that it pulls no punches in its depiction of the tycoon-turned-president.

It stars Sebastian Stan, best-known for playing the Winter Soldier in Marvel films and rocker Tommy Lee in series "Pam and Tommy".

Meanwhile, Demi Moore has emerged as a serious contender for the best actress award after rave reviews for her "fearless" performance in "The Substance", an ultra-gory horror about the pressures women face to maintain bodily perfection as they age.

Moore underwent up to eight hours of makeup for the hideous deformities that appear on-screen as her character tries a mysterious substance in a bid to look better.

"My little dog... always recognised me. That's all that counted," Moore joked to reporters, accompanied by her Chihuahua dog Pilaf.

"It was a very raw experience," she said, requiring her to "expose myself emotionally and physically."

The festival has so far seen 11 of the 22 entries for its top prize, the Palme d'Or, which will be decided by a jury led by "Barbie" director Greta Gerwig at Saturday's award ceremony.

For now, the frontrunner is considered to be "Emilia Perez", a highly audacious musical about a Mexican narco boss having a sex change.

It has earned acclaim for stars Zoe Saldana, Selena Gomez and trans actor Karla Sofia Gascon in the title role, as well as its French director, Jacques Audiard, who already has a Palme d'Or under his belt.

Also premiering on Monday is the latest from David Cronenberg -- director of body-horror classics like "The Fly", "Crash" and "Videodrome".

Billed as his most personal film yet, it tells the story of a widowed businessman (Vincent Cassel) who invents a machine to monitor the dead in their graves.

It was partly inspired by the death in 2017 of Cronenberg's wife of 43 years.

"I don't really think of art as therapy," the Canadian director told Variety. "Grief is forever... I didn't experience any catharsis making the movie."

Among entries scoring well with critics during the first week was "Bird", a gritty but sweetly fantastical tale about a young girl in working-class England from director Andrea Arnold.

"Kinds of Kindness", the latest bizarro team-up between Emma Stone and Yorgos Lanthimos, featured some ultra-dark comedy moments, including a thumb-and-cauliflower dinner.

"Megalopolis", the decades-in-the-making epic from Francis Ford Coppola, has perhaps been the most divisive entry, with some reviewers finding it a profound end-of-life work of philosophy, and others a barely comprehensible mess.

The festival has also seen glitzy out-of-competition launches for two Hollywood "sagas".

The action-packed "Furiosa: a Mad Max Saga" received mostly strong reviews, while Kevin Costner returned to his favourite Western genre with the three-hour "Horizon: An American Saga", just the first of four mooted chapters.

Like Coppola, Costner put millions of dollars of his own fortune into the decades-long passion project.

"At a certain moment I just said OK, I'm going to do this myself. And so I mortgaged property, I raised the money," he told AFP at the festival.

The early reviews were mixed, with The Hollywood Reporter deriding it as a "clumsy slog" while British newspaper The Telegraph said it was "earnest yet hopeful... (and) perhaps its full grandeur won't be fully realised until part two".

Costner says he is unconcerned about risking his money.

"If they take it away from me, I still have my movie. I still have my integrity. I still listened to my heart," he said.

'Emilia Perez' is the current frontrunner among critics
'Emilia Perez' is the current frontrunner among critics AFP
Emma Stone starred in the twisted comedy "Kinds of Kindness"
Emma Stone starred in the twisted comedy "Kinds of Kindness" AFP
Anya Taylor-Joy starred as Furiosa in the latest Mad Max
Anya Taylor-Joy starred as Furiosa in the latest Mad Max AFP
Demi Moore is a frontrunner for best actress for gory horror 'The Substance'
Demi Moore is a frontrunner for best actress for gory horror 'The Substance' AFP