American congresswoman Alexandria Ocasio-Cortez has sparked anger after calling President Donald Trump’s border detention facilities for Mexican immigrants as “concentration camps.”

Speaking on an Instagram Live video on Monday, the young New York Democrat - who stunned the party by taking a seat from a party grandee last year - said: “The US is running concentration camps on our southern border, and that is exactly what they are.

“If that doesn’t bother you … I want to talk to the people that are concerned enough with humanity to say that ‘never again’ means something.”

The Twitter account of the Auschwitz Museum said: "While the story of Auschwitz is complex as it was both a concentration & extermination camp in a context of war & occupation, the 12-year history of development of concentration camps in Nazi Germany is more complicated."

The Republican Jewish Coalition said it was a “disgrace” that she had invoked the deaths of six million Jews.

Fox News presenter Bill Hemmer even said Ms Ocasio Cortez owed “every Jew on this planet” over her remarks and also demanded to know if the Congresswoman had ever visited Auschwitz or even been to the American border herself.

Ms Ocasio-Cortez doubled down, tweeting on Tuesday: “This administration has established concentration camps on the southern border of the United States for immigrants, where they are being brutalized with dehumanizing conditions and dying...

“This is not hyperbole. It is the conclusion of expert analysis.”

She added: "For the shrieking Republicans who don't know the difference: concentration camps are not the same as death camps.

"Concentration camps are considered by experts as 'the mass detention of civilians without trial'. And that's exactly what this administration is doing."

Ms Ocasio-Cortez also described how some migrant children were being held in facilities formerly used to detain Japanese Americans during the Second World War.

America’s Department of Homeland Security (DHS) has said it was overwhelmed by the number of people illegally crossing the southern border.

The DHS said in May that it "has implemented a multi-layered approach" that includes the construction of additional structures to house migrants, continued coordination with Immigration and Customs Enforcement and providing staff support.

At 29, Ms Ocasio-Cortez is the youngest woman to ever serve in the House of Representatives.

She previously criticised Israel over what she described as a “massacre” in Gaza during the 2018 border protests.

But she has said she favours a “two-state solution” in the Middle East – although she once described Israel’s presence in the West Bank as an “occupation.”