Bernie Sanders has said he never expected to see a Nazi flag at a major political rally in his lifetime after a man unfurled a swastika during his speech at an event on Thursday.

The Democratic presidential candidate, who is campaigning to become America’s first Jewish president, described the incident at his rally in Arizona as “disgusting” and “horrible”.

Supporters of Mr Sanders immediately began booing when the flag was spotted and ripped it from the man, who was then ejected from the venue.

“We lost 400,000 people fighting that symbol, fighting Nazism, 6 million Jews were killed, other people were killed,” Mr Sanders told CNN’s Jake Tapper on Sunday.

“[It was] the most devastating war in the history of humanity and you have in the United States of America somebody who is an antisemite, [he was] yelling out vulgar things as well – obviously, it is unspeakable, it’s disgusting.”

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He added: “I've got to tell you, I never expected in my life as an American to see a swastika at a major political rally. It's horrible.”

The Vermont senator said he did not see the flag at the time but was told about it soon after leaving the stage in Phoenix.

Many of Mr Sanders’ family members were killed in the Holocaust during World War II.

Video from the event also appeared to show the man, who has been identified as a local far-right “stunt activist”, performing a “Heil Hitler” salute before he was escorted out of the rally.

Joe Biden, Mr Sanders’ rival for the 2020 Democratic nomination, denounced the flag-waver on Friday and expressed his support for the senator.

“I don't care who you're supporting, attacks like this against a man who could be the first Jewish president are disgusting and beyond the pale,” Mr Biden said on Twitter.

The American Jewish Committee (AJC), one of the oldest Jewish advocacy groups in the US, said it was “grateful” that the man was removed quickly from the venue.

“Nazi flags are symbols of pure hate and have no place anywhere in America, much less in a rally for a Jewish presidential candidate,” the AJC said.

Antisemitic incidents are at near-record levels in the US after surging in 2017, according to the Anti-Defamation League (ADL).

Figures released in May last year showed 2018 was the third-highest year on record for assault, harassment and vandalism against Jewish people since the organisation began recording data in 1979.