(CNN)-- Nearly one of every 10 state prisoners is sexually victimized during confinement, according to a Justice Department study released Thursday.
The Bureau of Justice Statistics examined data collected in surveys of former prisoners about their time behind bars. The officials found that most of the victims had been abused while they were in state prisons, but a small percentage were molested in local jails or halfway houses.
The victimization rate of 9.6% is more than double the rate cited in a report on the subject in 2008. However, the Bureau of Justice Statistics, an arm of the Justice Department, cautioned that the previous study was based on a survey of current inmates in both state and federal institutions.
The nature of the sexual incidents did not change. Female prisoners were more than three times as likely to be victims of sexual abuse as male prisoners.
Prison staff sexual misconduct was prevalent. The study noted nearly seven in eight such incidents involved perpetrators of the opposite sex. More than 75% of the former prisoners who reported staff sexual misconduct were male inmates who said they had interaction with female staff, the report said.
Violence associated with the sexual incidents was found to be common.
"Among all victims of inmate-on-inmate sexual violence, a quarter said they had been physically held down or restrained, and a quarter had been physically harmed or injured," the report said. About 29% of the victims reported bruises, black eyes, sprains, cuts and scratches, but 23% reported more serious injuries, including stab wounds, internal injuries, and broken bones.
In response, the Justice Department announced it is establishing rules "to prevent, detect, and respond to sexual abuse in confinement facilities"
The steps include screening inmates for risk of being sexually abused or sexually abusive, and training prison employees.
"The standards we establish today reflect the fact that sexual assault crimes committed within our correctional facilities can have devastating consequences for individual victims and for communities far beyond our jails and prisons," Attorney General Eric Holder said in a written statement.