Watch: Robert De Niro F-bombs Fox News, compares US President Donald Trump to 'a gangster'

Robert De Niro attends the world premiere of The Irishman at the New York Film Festival on Friday. Photo / AP.

Hollywood star Robert De Niro has launched an F-bomb laden attack on his Fox news critics and compared US President Donald Trump to a "gangster".

Speaking with CNN Business' Brian Stelter on Reliable Sources on Sunday, De Niro said be believed Democrats had no option but to open an impeachment inquiry into Trump.

"This guy should not be President, period," the star of The Irishman explained.

—@BrianStelter asks Robert De Niro about criticism he gets from Fox for speaking out against Trump.

"Fuck em," De Niro replies. "Fuck em."

Stelter reminds him, "This is cable, so it's not an FCC violation, but it is still a Sunday morning." pic.twitter.com/9IOo1VvXCM

— Oliver Darcy (@oliverdarcy) September 29, 2019

Things quickly escalated when Stelter reminded the 76-year-old actor that he had previously come under fire from Fox News, for his outspoken views on the president.

"F*** 'em," De Niro replied. "F*** 'em."

Stelter reminded De Niro his harsh language was not suitable for his show's Sunday morning audience and asked him: "Why do you choose to go that way?"

De Niro, who has made a career playing fearsome mafia figures and plays mob hitman Frank Sheeran in The Irishman, told Stelter that America was in a "terrible situation" under Trump's leadership.

De Niro attends a premiere for Joker at the Toronto International Film Festival. Photo / AP.

"Let me say something - we are in a moment in our lives where this guy is like a gangster," he said.

"He's come along and he's said things, done things. We say over and over again… this is terrible…we're in a terrible situation. We're in a terrible situation.

"And this guy just keeps going on and on and on without being stopped."

De Niro's outburst comes after he spoke at last year's Tony Awards, where he said "F*** Trump" twice. He received a standing ovation from the audience, but was heavily criticised by Fox News.

Speaking at the premiere of The Irishman at the New York Film Festival on Friday, De Niro told Variety he hopes Trump gets impeached.