Migrant children under the care of United States Customs and Border Protection (CBP) were allegedly beaten, threatened with sexual violence and repeatedly assaulted while in custody between 2009 and 2014, according to a report released Wednesday from the American Civil Liberties Union (ACLU) and the International Human Rights Clinic at the University of Chicago Law School.

Based on 30,000 pages of documents obtained through a records request, the report includes gruesome, detailed accusations of physical and mental abuse at the hands of officers. The claims were filed by unaccompanied minors, most of whom hailed from El Salvador, Guatemala, Mexico and Honduras. CBP officials have contested large swaths of the report, telling Newsweek that many of the allegations have been investigated and are "false."

Border authorities were accused of kicking a child in the ribs and forcing a 16-year-old girl to "spread her legs" for an aggressive body search. Other children accused officers of punching a child in the head three times, running over a 17-year-old boy and denying medical care to a pregnant teen, who later had a stillbirth.

Mitra Ebadolahi, ACLU Border Litigation Project staff attorney, said the allegations describe a law enforcement system "marked by brutality and lawlessness." The organization also accused Border Protection officials of failing to "meaningfully investigate" the allegations detailed in the public records.

"All human beings deserve to be treated with dignity and respect regardless of their immigration status—and children, in particular, deserve special protection," she said. "The misconduct demonstrated in these records is breathtaking, as is the government's complete failure to hold officials who abuse their power accountable."

In a call with reporters on Wednesday, ACLU staff and researchers from the International Human Rights Clinic said that the allegations, which took place during the presidency of Barack Obama, are especially alarming now that President Donald Trump has vowed to beef up the detentions of undocumented immigrants.

"The fact that these children were already so vulnerable—most traveling alone in hopes of escaping violence and poverty in their home countries—made the unlawful and inhumane actions reflected in the documents even more distressing," Claudia Flores, faculty director of the International Human Rights Clinic at University of Chicago, said in a statement to Newsweek.

In response to the allegations, Dan Hetlage, a spokesperson for the Border Control department, accused the ACLU of presenting accusations against CBP officers as fact. The department also accused the ACLU of deliberately littering the report with vague anecdotes. Without specifics, Border Protection cannot take "reasonable steps" to examine or address the accusations, Hetlage said.

"The false accusations made by the ACLU against the previous administration are unfounded and baseless," Hetlage said. "The 'report' equates allegations with fact, flatly ignores a number of improvements made by CBP as well as oversight conducted by outside, independent agencies, including the DHS Office of Inspector General and the Office of Civil Rights and Civil Liberties over the last decade."

Katie Waldman, a spokesperson for the Department of Homeland Security, echoed Hetlage's concerns, telling Newsweek the report is "absurd."

"They are without merit," she said. "Packaging dozens of patently baseless allegations and calling it a 'report' does not change the facts—it is just a collection of patently baseless allegations."

This story has been updated to include a comment from the Department of Homeland Security.

Central American migrants travelling in the 'Migrant Via Crucis' caravan sleep outside 'El Chaparral' port of entry to US while waiting to be received by US authorities, in Tijuana, Baja California State, Mexico on April 30, 2018. The ACLU released a new report detailing abuse allegations minors have made against CBP officers. Guillermo Arias/AFP/Getty Images