By Stephanie Nebehay
GENEVA (Reuters) - The United Nations' human rights chief expressed concern on Thursday at what she said were plans by the U.S. government to deport tens of thousands of unaccompanied children who entered the United States in recent months.
Around 57,000 children from Central America were detained at the U.S.-Mexico border after crossing the frontier without their parents in the nine months to June 30.
Faced with a delicate and divisive political issue, President Barack Obama's administration has said most will be sent home as they would not qualify for asylum or refugee status.
Navi Pillay, U.N. High Commissioner for Human Rights, urged Washington to protect the child migrants and investigate dozens of reports of abuse against them by U.S. officials.
"I am particularly concerned because the United States appears to be taking steps to deport most of these children back," Pillay told a final news briefing in Geneva before completing six years in office on Aug. 31.
"There are almost 100 reports of physical, verbal and sexual abuse by agents towards the children, filed in a complaint by NGOs (non-governmental organizations)," Pillay said.
"The United States does need to urgently investigate all alleged human rights abuses against children and severely sanction perpetrators," the former U.N. war crimes judge said.
Obama urged the leaders of Guatemala, Honduras and El Salvador last week to work with him to stem the flow of child migrants and said most would not be allowed to stay as they would qualify for humanitarian relief or refugee status. [ID:nL2N0Q026T].
But Pillay said children should only be deported if their protection was guaranteed in the countries that are returned to.
Those needing international protection should be identified and granted protection in the United States, she said.
Mandatory detention of child migrants should only be a "last resort option" as it contravenes the legal principle of upholding a child's best interests, she added.
Obama's drive to tackle the migrant crisis with $3.7 billion in emergency funds has hit trouble because the deeply divided Congress leaves on a month-long recess at the end of Friday.
John Cornyn of Texas, the No. 2 Republican in the U.S. Senate, said on Sunday that he expected the House of Representatives to pass a "skinnied-down" emergency funding bill this week to deal with the crisis. [ID:nL20Q20E2]
Pillay said: "I recognize that there is a complicated political situation and we are in a position to offer assistance and advice and we do so."
In the meantime, the United States must provide migrant children with services to support their "physical, psychological and emotional recovery," she said.
(Editing by Robin Pomeroy)