The United Nations human rights office said it is "deeply concerned" with the Trump administration's policy of separating migrant children from their families at the border.

"We are deeply concerned that the zero tolerance policy recently put in place among the US southern border has led to people caught entering the country irregularly being subjected to criminal prosecution and having their children — including extremely young children — taken away from them as a result," Ravina Shamdasani, a spokesperson for the Office of the High Commissioner for Human Rights (OHCHR), said in a statement released on Tuesday.

There were 500 children in custody at US border stations as of Sunday, according to NBC News, of whom nearly 300 have been held for longer than the 72 hours any immigrant can be held in the temporary facilities the Border Patrol controls.

"The separation of families amounts to arbitrary and unlawful interference in family life, and is a serious violation of the rights of the child," the UN statement continues. It notes that the US is the only country in the world that has not signed on to the Convention of the Rights of the Child. Somalia, previously the only other remaining holdout, ratified the treaty in 2015.

"The US should immediately halt this practice of separating families and stop criminalizing what should be at most an administrative offence — that of irregular entry or stay in the US," the statement said. "We call on the US authorities to adopt non-custodial alternatives that allow children to remain with their families and fulfill the best interest of the child, their right to liberty, and right to life."

The UN also called out human rights abuses in Ethiopia and Egypt alongside the US in Tuesday's statement.

US Ambassador to the UN Nikki Haley pushed back on the criticism, saying OHCHR had "ignorantly" attacked the US and that the UN has a whole had shown its "hypocrisy" by calling out the United States instead of members of the UN's Human Rights Council.

"We will remain a generous country, but we are also a sovereign country, with laws that decide how best to control our borders and protect our people," Haley said in the statement. "Neither the United Nations nor anyone else will dictate how the United States upholds its borders."



Outrage over the "zero tolerance" policies that US Attorney General Jeff Sessions announced in April, which ordered illegal crossings to be immediately be referred to federal prosecutors, has spiked in recent weeks as stories of migrant parents unsure of where their children are being held have begun trickling out. That has only been augmented by reports that even parents entering the country legally have been separated from their children, as in the case of one woman from El Salvador seeking asylum.

Last week, a group of petitioners filed a complaint against the US at the Inter-American Court of Human Rights for violating migrants' human rights by separating families. “In one particularly chilling example," the attorneys and advocates who filed the complaint on behalf of their clients wrote, "immigration agents told two immigrant mothers that they were taking their daughters away to the bath — but they never returned, and the mothers have not seen them since."

Prince Zeid Ra’ad Al Hussein, the UN's high commissioner of human rights, has been critical of Trump's policies since even before the 2016 election.

“The United States is a republic founded on the dignity of the individual, the rights of the individual,” Prince Zeid said in 2016 about Trump's proposed travel ban, which is still being debated in court. “The danger of classification and categorization … dehumanizes. It can lead to victimization of the innocent.”