US actor Sean Penn attends a press conference for the film Black Flies during the 76th edition of the Cannes Film Festival in Cannes, southern France, on May 19, 2023. (Photo: AFP)
Penn was speaking at the Cannes Film Festival, the day after the premier of his new film, "Black Flies", an ultra-gritty movie about New York paramedics.
Asked about the writers' strike that has upended Hollywood productions, he said: "It is the industry that's been upending the writers and the actors and directors for a very, very long time. My full support in this situation is with the writers guild of course.
"There are a lot of new concepts that are being tossed about, including the use of AI (to write scripts). It strikes me as a human obscenity for there to be any pushback on that from the producers."
The strike kicked off on May 3 after negotiations broke down between the Writers Guild of America and major US studios, with writers demanding better compensation after the disruption caused by streaming and fears over the increasing use of AI.
"The first thing we should do in this conversation is change the Producers Guild and title them how they behave, which is the Bankers Guild," Penn said.
The strike has been a hot topic at the festival.
James Mangold, director of "Indiana Jones and the Dial of Destiny", also backed the striking writers.
"No movie happens without a great script, and no great script happens without writers. I support them in their struggle," he told reporters.
On Tuesday, US actor and director Paul Dano -- who is on the festival jury -- added his support, saying he would join the picket line when he got home.
The 62-year-old Penn has long been an outspoken activist and runs a disaster relief organisation overseeing a huge testing and vaccination programme during the peak of the Covid-19 pandemic.
He and young star Tye Sheridan ("Ready Player One") spent many hours riding along with New York paramedics for the no holds barred look at their profession in "Black Flies".
"They're our guardian angels and we don't put enough emphasis around their jobs and their mental health, and the film is very confrontational with that," said Sheridan.
Asked about the state of the US health system, Penn said it was "a racket".
"We saw it every night -- you collect bodies to bring in and you hear the ching-ching of insurance and money changing hands for everybody but those they're taking it from," he said.
Director Jean-Stephane Sauvaire joked that Penn got so much training that "you don't have to call 911 in New York any more: if you have a problem, you just call Sean".