A new report says there was widespread abuse of immigrant children detained by U.S. Customs and Border Protection during President Barack Obama’s administration.

CBP said the accusations are false.

The report, which was written by the International Human Rights Clinic at the University of Chicago Law School, is based on thousands of pages of government documents from between 2009 and 2014. The American Civil Liberties Union got the documents through the Freedom of Information Act. The report concluded there is evidence of systemic abuse of immigrant children by CBP throughout the Southwest.

“The abuses include physical, sexual and psychological abuse, and reveal mistreatment that is neglectful at best, and intentionally cruel at worst,” said Mitra Ebadolahi, staff attorney for the ACLU’s Border Litigation Project.

CBP spokesperson Dan Hetlage responded in a prepared statement.

“The false accusations made by the ACLU against the previous administration are unfounded and baseless,” the statement 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 (OIG) and the Office of Civil Rights and Civil Liberties over the last decade.

"The OIG has already completed an investigation and found these claims unsubstantiated and did not observe misconduct or inappropriate conduct. CBP takes seriously all allegations of misconduct, but without new specifics is unable to check to commence reasonable steps to examine these assertions and address the accusations levied.”