Donald Trump’s rhetoric about “good genes” is “indistinguishable from the Nazi rhetoric” during the Second World War, an expert on the Holocaust has said.

The US president praised the genes of Minnesotans during a campaign rally in the city of Bemidji last week, during which he also derided refugees, gloated about a reporter being shot with a rubber bullet, and praised a general who fought for the Confederacy during the American Civil War.

“This state was pioneered by men and women who braved the wilderness and the winters to build a better life for themselves and for their families. They were tough, and they were strong. You have good genes, you know that, right?” Mr Trump said to applause from supporters.

“You have good genes. A lot of it’s about the genes isn’t it, don’t you believe? The racehorse theory you think was so different? You have good genes in Minnesota.”

Mr Trump’s comments were widely condemned as echoing the language of racist eugenicists, who believe the human race can be improved genetically by selective breeding.

“As a historian who has written about the Holocaust, I’ll say bluntly: This is indistinguishable from the Nazi rhetoric that led to Jews, disabled people, LGBTQ, Romani and others being exterminated,” Steve Silberman, an acclaimed science writer who has covered the Nazi treatment of people with autism, said on Twitter.

“This is America 2020. This is where the GOP has taken us.”

Eric Feigl-Ding, an epidemiologist and senior fellow at the Federation of American Scientists, said Mr Trump’s comments mirrored “master race eugenics”.

He added: “This was how the Holocaust started. Don’t ignore.”

The US president has a long history of praising the role of genes in human capabilities, and has repeatedly commended himself for his “great” and “winning” genes.

In 2016, Mr Trump’s biographer revealed Mr Trump believed in the “racehorse theory” of genetics, and that his father, Fred Trump, had taught his son the family’s success was due to their genes.

“The family subscribes to a racehorse theory of human development,” Michael D’Antonio told PBS.

“They believe that there are superior people and that if you put together the genes of a superior woman and a superior man, you get a superior offspring.”

In undated video footage unearthed by the Huffington Post, Mr Trump, before becoming president, denied that “all men are created equal”.

“Well it’s not true, because some are smart, some aren’t,” he said.

In separate footage, Mr Trump said: “I’m proud to have that German blood. There’s no question about it.”