Cher has savaged Republican presidential nominee Donald Trump, comparing him to Stalin, Hitler and a murderous film character.

The Believe singer spoke at a private fundraiser for the billionaire businessman’s Democratic rival Hillary Clinton and gave a stinging assessment of Trump.

Invoking the film The Bad Seed, she told the event in Provincetown, Massachusetts, on Sunday: “He’s so Patty McCormack, consummate liar, doesn’t care who she hurts, insane.”

Cher leaving the fundraiser for Hillary Clinton in ProvincetownCher leaving the fundraiser for Hillary Clinton in Provincetown (Carolyn Kaster/AP)

Before an enthusiastic crowd, Cher also said of Trump: “Do you remember Fun With Dick And Jane? It’s like racist fun with Dick and Jane.”

She later added: “He doesn’t mean we want to make America great again. He means we want to make America straight and white.”

She also said that she was reminded of “despots, you know Stalin and Hitler”.

Republican presidential candidate Donald Trump speaks during a town hall campaign at Ocean CentreDonald Trump (Evan Vucci/AP)

A video of Cher’s remarks at the “LGBT summer celebration” was posted on Facebook.

Cher, who has been campaigning with Clinton, offered praise, though with a few caveats.

“She is shy and she’s not the greatest speaker in the world,” Cher said. “But this is what I believe and this is what I know. I know she will work every moment of every day.”

Cher fans in ProvincetownCher fans in Provincetown (Carolyn Kaster/AP)

After the event, Cher told reporters that Trump was “a racist, he’s a misogynist, he’s a horrible person”.

A partial clip of Clinton’s remarks was also posted on Facebook. Thanking Cher, she said: “I can’t tell you how excited I am to have Cher here.”

A popular entertainer for decades, Cher came to fame in the 1960s as part of a singing duo with then-husband Sonny Bono.

She has enjoyed success as a solo artist, with songs like If I Could Turn Back Time and Believe, and has starred in films including Moonstruck, Silkwood and Mermaids.