According to the US Republican Senator Rob Portman, US Department of Health and Human Services (HHS) has released at least six unaccompanied children from Guatemala to guardians who exploited them, which was made possible by the HHS not conducting the proper background checks.
US Senate investigation is underway due to a case in Portman's home state of Ohio, where six people have been charged, Portman said.
Case was prompted when Department of Health and Human Services adopted at least six children from Guatemala to people who forced them to work long hours on egg farms in Marion County, HHS did not have the proper procedures in place to protect undocumented children who were entering the United States without an accompanying adult.
That could have been prevented had HHS adopted measures on screening sponsors and checking on the well-being of at-risk children, Portman said.
HHS Acting Assistant Secretary Mark Greenberg, gave the number of refugee children in temporary care of the HHS as having jumped from an average of around 6,000 a year to 57,496 in 2014 and 33,726 in 2015.
"It is intolerable that human trafficking - modern-day slavery - could occur in our own backyard," Portman said. "But what makes the Marion cases even more alarming is that a US government agency was responsible for delivering some of the victims into the hands of their abusers."
According to Portman's statement, HHS has placed around 90,000 refugee children with adult sponsors in the US, most of whom come from Central America.
President Barack Obama's administration has been criticised by Republicans in 2014 for its refugee policy after undocumented minors slipped across the southern border.
Despite the US government's subsequent efforts to discourage migration, number of undocumented families and unaccompanied children from Central America rose significantly late last year, according to US figures.