CUMBERLAND — A Western Maryland juvenile detention center had the highest rate of sexual abuse in a nationwide study released earlier this week, prompting the state Department of Juvenile Services to launch an independent investigation of the claims.

The U.S. Justice Department report indicates that four of 11 youth at Backbone Mountain Youth Center in Garrett County said they had been sexually abused by staff or another youth in the last year.

That rate — 36.4 percent — was the highest of 195 juvenile detention centers surveyed across the country.

Nationwide about 12 percent of youths held in state-run, privately run, or local facilities reported some type of sexual victimization, the report showed. The rates varied widely between facilities.

Victimization included forced sexual activity with another youth and all sexual activity with staff.

Maryland Department of Juvenile Services officials were “shocked” to learn the findings of the report, Jay Cleary, director of communications, said in a prepared statement released Thursday. The juvenile services agency has not had any substantiated complaints of sexual abuse at Backbone Mountain, and only one such allegation since 2007, he said.

“DJS takes the issue of sexual abuse of juveniles very seriously,” Cleary said, adding that when Maryland DJS officials agreed to participate in the study a year ago, they were “adamant” that any allegations of sexual abuse raised by the participating youth must be reported to Maryland Child Protective Service and law enforcement in accordance with state law.

“Despite DJS’ admonition, the surveyors declined to report,” Cleary said.

The survey, conducted for the government by Westat, a research company in Rockville, included information from about 9,000 youth collected via anonymous computerized questionnaire. Conducted from June 2008 to April 2009, it asked whether the young inmates had been abused in the previous year of detention.

A spokesman for Westat couldn’t be reached Friday.

Although advocates said the level of abuse wasn’t surprising, the prevalence of sexual abuse by staff, particularly female workers, was shocking, said Linda McFarlane, deputy executive director of Just Detention International, which fights to end sexual abuse of those who are detained.

About 10 percent of youths surveyed reported abuse involving facility staff, and nearly all of those complaints were against female staffers, who made up less than half of the workers. About 2 percent of the reported abuse involved other young inmates.

“Many of these are already the most vulnerable and traumatized youth from all of our communities and they’re placed for custody because they’re considered to be a danger,” McFarlane said. “If sexually abused in those very institutions that are supposed to help them prepare for life in the community, then it’s just an incredible travesty.”

The study identified six facilities where the survey found at least three out of every 10 inmates said they were sexually victimized while in custody: Pendleton Juvenile Correctional Facility in Indiana; Corsicana Residential Treatment Center in Texas; Backbone Mountain Youth Center in Swanton; Samarkand Youth Development Center in Eagle Springs, N.C.; Cresson Secure Treatment Unit in Pennsylvania; and the Culpeper Juvenile Correctional Center, Long Term, in Mitchells, Va.

Another seven sites reported nearly as high levels of sexual abuse or victimization: Victory Field Correctional Academy in Vernon, Texas; Indianapolis Juvenile Correctional Facility; Shawono Center in Grayling, Mich.; Woodland Hills Youth Development Center in Nashville; L.E. Rader Center in Sand Springs, Okla.; Bon Air Juvenile Correctional Center in Virginia; and New Jersey Training School in Monroe Township.

The numbers were far different than the records kept by many states. Officials in several states, including Pennsylvania, North Carolina, Tennessee, New Jersey and Maryland, said they had very few or no substantiated complaints of sexual abuse in recent years at the facilities named in the report.

In Maryland, the DJS is working with the Department of Human Resources and the Department of Health and Mental Hygiene to conduct an internal investigation, a spokeswoman said. That study is expected to be completed in about a week, she said.