Teenagers protested the US immigration policy of separating parents and children at the Mexican border on Monday by getting into cages in front of the Geneva headquarters of the United Nations.
The protesters wore shirts marked #ClassroomsNotCages and carried signs saying "Summer camps, not detention camps."
The action came as a UN Human Rights Council panel is to start reviewing a complaint filed last year by the American Federation of Teachers (AFT) denouncing what it describes as an "inhumane" policy.
AFT President Randi Weingarten said the protest aimed to "expose the injustice being done, the deprivation being done to children who have been separated from their parents, from their families at the southern border of the United States and Mexico."
"We believe that 2,500 children have been separated from their parents in the last year. There are court cases after court cases, where the Trump administration have been told to reunite children with their parents, that has not happened. Instead, the Trump administration has pleaded that they don't know how to reunite, that they don't know, they don't have the records," she added.
The US and Mexico struck a deal earlier this month which forces asylum seekers from Central America to await the reply to their US asylum application in Mexico.