British director Ken Loach's film I, Daniel Blake has won the Palme d'Or at Cannes Film Festival.
It was the 79-year-old's second award for best picture at the festival after 2006's The Wind That Shakes the Barley.
Loach attacked the "dangerous project of austerity" as he accepted the award for his film about a middle-aged widower and the UK welfare system.
Kent-born director Andrea Arnold won the competition's Jury Prize for her road movie American Honey.
Irish cinematographer Robbie Ryan shot both films.
It was the 13th time Loach, a social campaigner for most of his career and the director of more than 50 movies, has competed at the event.
I, Daniel Blake, which stars stand-up comedian Dave Johns in the title role, was written by long-time Loach collaborator Paul Laverty.
It documents what happens when an older man living in Newcastle has a heart attack and can no longer do his job.
He is declared fit for work, meaning his benefits are stopped, and he begins to go hungry.
Accepting the festival's top prize from actor Mel Gibson, Loach said: "We must give a message of hope, we must say another world is possible.
"The world we live in is at a dangerous point right now. We are in the grip of a dangerous project of austerity driven by ideas that we call neo-liberalism that have brought us to near catastrophe."
Loach told a press conference after he was "quietly stunned" to have won the award with "the same little gang" from his first win in 2006.
Asked about his plans for the future, Loach gave nothing away, saying: "When you get very old you're just pleased to see the sunrise the next day, so we'll just take each day as it comes."
In the film, Johns meets single mother of two Katie, who moves to Newcastle from London.
Cannes judges praised the actors' depictions of the characters who "find themselves in no-man's land, caught on the barbed wire of welfare bureaucracy as played out against the rhetoric of 'striver and skiver' in modern day Britain".
I, Daniel Blake marked the first film role for Johns, who said he was delighted by the French film prize.
He said: "Ken made a film 50 years ago called Cathy, Come Home and this is actually in the same vein, saying that people who are on the bottom rung of life, you know are struggling."
Speaking to BBC Radio 4's Today programme, Loach said: "If you get out among the people who are in the food banks, who would not eat unless there were people providing charity, I think you'd find there's a great disgust and despair that we live like that in this country now."
Loach, whose past films include 1969's Kes, was up against directors including Spanish Oscar-winner Pedro Almodovar, Sean Penn and Paul Verhoeven.
The Iranian film Forushande (The Salesman) by Asghar Farhadi won two awards - best screenplay and best actor, won by Shahab Hosseini.
The Grand Prix went to Juste la Fin du Monde (It's Just the End of the World), directed by Canada's Xavier Dolan, while Philippine soap star Jaclyn Jose won best actress for her role in Brillante Mendoza's Ma' Rosa.
Andrea Arnold, originally from Dartford, Kent, won the competition's Prix du Jury (Jury Prize).
American Honey, starring Hollywood star Shia LaBeouf, follows a group of wild youths as they travel through US states selling hard luck stories and magazine subscriptions.
Ben Roberts, director of the BFI Film Fund, said: "What a moment for British cinema, and for two important and humane films with so much to say.
"Bravo to Ken and to Andrea and their collaborators - including the unstoppable Robbie Ryan who shot both films.
"This is cinema from the heart, and we're grateful that we have an industry that can support such personal, powerful film-making."
Film critic Jason Solomons said Loach's movie cut through the art and experimentation common at Cannes to "speak to the heart".
"Ken Loach does that with unparalleled skill," he said. "You know it's such an important movie and I'm so glad that it won the Palme D'Or because it gives this movie and its message extra attention that it needs."