Sean Penn has expressed his solidarity with the Writers Guild of America (WGA), whose members are currently on strike in a fight for improved wages and working conditions.

Speaking at a press conference in Cannes for his new film, Black Flies, Penn said the guild had his “full support” as “the industry has been upending the writers and actors and directors for a very, very long time.”

The WGA strike, which began more than a fortnight ago, shows no sign of reaching a resolution as its members seek a renegotiated contract in the streaming era.

“There are a lot of new concepts being tossed around,” Penn continued, “including the use of AI. And it just strikes me as a kind of human obscenity for there not to have been any pushback on that.”

Suggestions that the Screen Actors Guild members may soon join their WGA colleagues on the picket lines have led many to try and identify the key culprits in the battle between creatives and studios.

In Cannes, Penn attempted to place blame on the producers, saying “the first thing we should do in these conversations is change the Producers Guild and title them how they behave, which is the bankers guild.”

The film-maker was in town with Black Flies, about a young paramedic (played by Tye Sheridan) who struggles with an intense workload while manning an ambulance in Brooklyn. Penn plays a veteran co-worker who teaches him the ropes.

Penn won the best actor award at the festival in 1997 for She’s So Lovely and starred in Terrence Malick’s The Tree of Life in 2011, when it won the Palme d’Or.

Two of his directorial features have also premiered at the festival: 2001’s The Pledge, and 2016’s The Last Face, which was badly received and led to one of the festival’s most notoriously awkward press conferences.