By Lisa Lambert and Makini Brice
WASHINGTON (Reuters) - The Trump administration on Monday defended its hardline immigration policy at the U.S.-Mexico border as criticism mounted over detained immigrant parents being separated from their children, including video of youngsters sitting in concrete-floored cages.
While Democrats blasted such treatment as "barbaric" and some Republicans also voiced concerns, Department of Homeland Security Secretary Kirstjen Nielsen said the administration was only strictly enforcing immigration law.
"This administration did not create a policy of separating families at the border. ... What has changed is that we no longer exempt entire classes of people who break the law," she told reporters at a White House briefing.
The family separations result from Trump's "zero tolerance" policy that provides for the arrest of all adults caught trying to enter the United States illegally, including those seeking asylum.
While parents are held in jail, their children are sent to separate detention facilities. Video footage released by the government showed migrant children held in wire cages, sitting on concrete floors.
Democrats and some of Trump's own Republicans have admonished the administration for dividing nearly 2,000 children from their parents between mid-April and the end of May.
Trump, whose promise to crack down on illegal immigration has been a major theme of his campaign and presidency, responded sharply to critics on Monday.
"The United States will not be a migrant camp, and it will not be a refugee holding facility. It won't be. You look at what's happening in Europe, you look at what's happening in other places - we can't allow that to happen to the United States, not on my watch," Trump said at the White House while announcing an unrelated policy.
Trump has sought to use the widespread outrage over the family separations to push through other immigration priorities that have stalled in Congress, such as funding for his long-promised wall along the Mexican border.
He has blamed Democrats for the impasse, even though his fellow Republicans control both chambers in Congress. Democrats have accused the president of using children as hostages.
House Democratic leader Nancy Pelosi called the separation of children from parents "barbaric" and said Nielsen should resign. Pelosi made the comment after visiting a detention center for children at the border in California.
Republican Senator Pat Roberts tweeted: "While I firmly support enforcing our immigration laws, I am against using parental separation as a deterrent to illegal immigration. My concern, first and foremost, is the protection of the children."
Trump administration officials say the zero-tolerance policy, which was not practiced by the two previous administrations, is necessary to secure the border and deter illegal immigration.
Border crossings briefly dropped after Trump took office in January 2017, but have since risen to levels seen during the administration of his Democratic predecessor, Barack Obama. Almost 52,000 people were caught trying to cross the southern border illegally in May, according to government figures.
(Reporting by Lisa Lambert and Makini Brice; Additional reporting by Stephanie Nebehay in Geneva and Nathan Frandino and Yeganeh Torbati in Washington; Writing by Kevin Drawbaugh; Editing by Grant McCool and Peter Cooney)