US Attorney General Jeff Sessions has rejected claims US holding centres for child migrants separated from parents are like Nazi concentration camps.
America’s top law official told Fox News the “zero tolerance” policy was about enforcing border security.
President Donald Trump is meeting Republican lawmakers later to discuss a bill that proposes to curb the policy.
US immigration officials say 2,342 children have been separated from 2,206 parents from 5 May to 9 June.
Mr Sessions was asked in Monday night’s interview on Fox News about a tweet by former CIA Director Michael Hayden likening what happened at Auschwitz concentration camp, where millions of Jews and other minorities were killed, to the separation of undocumented immigrant families at the US border.
The Department of Justice chief said: “Well, it’s a real exaggeration, of course.
“In Nazi Germany, they were keeping the Jews from leaving the country.”
Mr Sessions said: “Fundamentally, we are enforcing the law. Hopefully people will get the message and not break across the border unlawfully.”
Fox News hosts Laura Ingraham said the detention centres were “essentially summer camps” for migrant children.
US First Lady Melania Trump and four of her predecessors are among critics of the policy.
Laura Bush said the detention centres reminded her of internment camps where Japanese-Americans were held during the Second World War.
What is the policy?
Under the “zero-tolerance” crackdown that the Trump administration rolled out in May, all border crossers – including first-time offenders – are criminally charged and jailed pending a court appearance.
Migrant children are not permitted to be incarcerated with their parents, and are kept in separate facilities maintained by the Department of Health and Human Services.
Under previous US administrations, undocumented immigrants caught crossing the border for the first time tended to be issued with court summons for a later date.
But the Trump administration says that approach amounted to “catch and release” because many of the migrants never showed up to court.
The Trump administration has been disputing the terminology used to describe its immigration crackdown.
The Department of Homeland Security has framed it as an “initiative” rather than “a policy”.
It characterises the holding centres where children have been pictured behind metal chain-link enclosures with concrete floors as “shelters” instead of “cages”.
Dictionary.com has reported a 279% increase in people searching for the word “cage” over the last day or so.
What are Trump and Congress doing?
On Tuesday afternoon, the Republican president is due to head to Congress, which is controlled by members of his party, as the House of Representatives prepares this week to vote on a moderate immigration bill.
The compromise measure would limit, but not outright ban family separations. It would also offer an eventual path to citizenship for undocumented adult immigrants, known as Dreamers, who entered the US as children.
The Republican legislation would also provide $25bn (£19bn) in funding for border security, including Mr Trump’s planned US-Mexico wall.
The White House says Mr Trump supports the package.
A hardline conservative immigration bill is also in circulation, though it lacks enough support to be politically viable.
More on US immigration
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