Benito Mussolini's granddaughter has hit out at actor Jim Carrey over a cartoon of the former Italian dictator.

The Canadian-American actor — also an artist — posted a picture of the pair hanging from their feet with the caption: "If you're wondering what fascism leads to, just ask Benito Mussolini and his mistress Claretta."

Carrey’s art is based on the real-life deaths of Mussolini and Claretta Petacci who were captured by communist partisans and executed by firing squad on April 28, 1945, two days before Adolf Hitler's suicide.

Alessandra Mussolini, 56, a former movie actress herself turned politician with the centre-right Forza Italia political party, responded to Carrey’s tweet on Sunday with one line: “You are a bastard."

Her initial responding comment triggered an online debate involving, among others, political communication specialist Evan O'Connell.

"I think you're confusing Jim Carrey with your murderous grandfather," he tweeted at Mussolini, who responded: “Or maybe with some of your family."

“My grandfather fought to liberate Europe from people like your grandfather," O'Connell retorted, prompting this from Mussolini: “Do you want applause?”

Mussolini's granddaughter went on to post an angry tweet storm in response to the cartoon calling out Carrey for not creating art about American historical embarrassments such as the treatment of Native Americans, Southern segregation and the dropping of atomic bombs on Japan at the end of World War II.

Carrey, who was born in Canada, has not responded to Mussolini's tweets.

The Hollywood star is best-known for his roles in films such as "Ace Ventura: Pet Detective", "The Truman Show" and "Liar, Liar", has rebranded himself as one of the most vocal anti-Trump political cartoonists.

Mussolini, a supporter of the US president, also tweeted Sunday that Trump doesnt have to worry about Carrey's political attacks because his drawing's are only "dirty paper."