WASHINGTON (AP) — The government reported Thursday that 4.4 percent of inmates in prison and 3.1 percent of inmates in jail report being victimized sexually by another inmate or staff member.

Those percentages translate to the sexual victimization of 88,500 inmates behind bars nationwide in the previous 12 months, according to a study by the Justice Department’s Bureau of Justice Statistics in 2008-2009.

The study found that:

—Female inmates were more than twice as likely as male inmates to report experiencing sexual victimization by another inmate.

—Among inmates who reported victimization by another inmate, 13 percent of male prison inmates and 19 percent of male jail inmates said they were victimized within the first 24 hours after being admitted to a corrections facility. In contrast, the figure for women was 4 percent for prison and jail.

Tens of thousands of rapes are occurring in America’s prisons each year and the new study “finds the problem is even worse than we thought,” Pat Nolan, vice president of Prison Fellowship, said in a statement.

In a letter earlier this month to Attorney General Eric Holder, a coalition of groups including the American Civil Liberties Union and the Southern Baptist Convention urged that he approve standards designed to eradicate sexual assault in prison. The standards were proposed by the bipartisan Prison Rape Elimination Commission, which was set up by 2003 law designed to end prison rape.

“We are working diligently to implement these standards as soon as possible” and expect to send the proposed rule to the White House Office of Management Budget in the fall, said Justice Department spokeswoman Hannah August.

Under the proposed standards, inmates would be screened for risk of victimization, procedures would be in place to manage inmate predators with prosecution where appropriate and there would be a focus on treatment and care of victims.

“I regret that we will not meet Congress’s deadline” of June 2010 for completing work on the regulations, the attorney general wrote in a recent letter to the two key sponsors of the Prison Rape Elimination Act of 2003. Holder wrote that he believes it is “essential to take the time necessary to craft regulations that will endure.”