GENEVA (AP) — The U.N.'s human rights chief has challenged Trump administration policies and said she is "appalled" by the conditions facing detained migrants and refugees in the United States.

United Nations High Commissioner for Human Rights Michelle Bachelet said Monday that children should never be held in immigration detention facilities or separated from their families.

She appealed for "non-custodial alternatives" for migrants and refugees who are caught entering the U.S. illegally.

U.N. rights office spokeswoman Ravina Shamdasani said the commissioner decided to speak out more forcefully than before after the Department of Homeland Security's inspector general issued a report last week warning of dangerous conditions in U.S. detention facilities.

Bachelet acknowledged the "sovereign prerogative" of countries to set the conditions under which foreigners are permitted to enter and stay but also highlighted their human rights obligations.