A coalition of advocacy groups is demanding immediate action to end what they say is mistreatment of unaccompanied minor immigrants at the hands of U.S. Customs and Border Patrol agents.

Children say they have been punched, kicked and raped while in custody, in a complaint with more than 100 allegations. Others say they were fed only frozen sandwiches, forced to drink toilet tank water or forced to use toilets in front of other detainees.

In a complaint filed Wednesday, one in four children reported some form of physical abuse, ranging from sexual assault to beatings to the use of stress positions.

Five victims' advocacy groups jointly filed the complaint with the Department of Homeland Security on behalf of 116 unaccompanied immigrant children, aged five to 17 years old.

There were multiple claims of sexual or racially-charged insults and strip searches.

A third of the children reported that money and personal belongings were confiscated and not returned.

The coalition says there is also the lack of basic care. In cases documented from March to May of this year, 80 percent of the children said they didn’t get enough food or water.

In a 2014 report that involved interviews of 224 young detainees, more than half of them said they were held in wrist and ankle shackles.

CBP officials say "mistreatment or misconduct is not tolerated" among its ranks. "While in temporary custody, CBP strives to protect unaccompanied children with special procedures and safeguards," it said in an official statement.

But the agencies' complaint lists personal stories from teenagers who say they had a far different experience.

A 13-year-old boy taken into custody in Texas says he was molested by two adult men in the holding cell where he spent the night.

A 17-year-old mother from Guatemala told the coalition that she and her one-year-old daughter were held for nine days. She said she didn’t receive diapers or food for the infant until the third day.

Another detainee, a 16-year-old male, said he and 40 other detainees were given a gallon of water to share.

Other minors said they couldn’t tell how long they had been in custody because the lights in their holding cells were never turned off.

Federal officials deny allegations that food and water are withheld from minor detainees. "Children are provided meals regularly and have access to drinks and snacks throughout the day," they said in a statement.

Under the 2008 Trafficking Victims Protect Reauthorization Act (TVPRA), children in custody of USCBP should get two hot meals every 24 hours. They are to be fed within eight hours of detention. Also, all children, toddlers, and babies and pregnant women are to have regular access to snacks, milk, and juice at all times.

No juvenile is to be held for more than five days.

CBP officials say the agency "does everything within its power to process these children as quickly as possible in order to transfer them to the Department of Health and Human Services within 72 hours absent exceptional circumstances, as required by law."

"In the face of overwhelming numbers of unaccompanied children crossing the border in South Texas," the statement continues, "U.S. Border Patrol agents have taken extraordinary measures to care for these children while in custody and to maintain security in overcrowded facilities."

The coalition wants the Department of Homeland Security to ensure no child is detained for more than 24 hours.

They also want CBP facilities to be staffed with people who are trained in child welfare and adopt a zero-tolerance policy for employees who abuse juvenile detainees.

“The sheer volume and consistency of these complaints reflects longstanding, systemic problems with CBP policy and practices,” the complaint reads.

The advocacy groups involved are the National Immigrant Justice Center, Esperanza Immigrant Rights Project, Americans for Immigrant Justice, Florence Immigrant and Refugee Rights Project and the ACLU Border Litigation Project.