WASHINGTON - The Justice Department is refusing to provide statistics to Congress that would show how many crimes the federal government declines to prosecute on reservations.

North Dakota U.S. Attorney Drew Wrigley delivered that message to frustrated senators at a hearing Thursday, saying that releasing the information could compromise the safety and privacy of victims and witnesses.

North Dakota Sen. Byron Dorgan, the Democratic chairman of the Senate Indian Affairs Committee, criticized the Justice Department for that decision, along with Sens. Lisa Murkowski, R-Alaska, and Jon Tester, D-Mont.

"Something's desperately wrong, and we need to find a way to fix it," Dorgan said.

Federal statistics have shown Native Americans are the victims of violent crime at 2.5 times the national rate, with rates of homicide and domestic violence much higher than national averages.

Dorgan has asked the federal government to elaborate on statistics released by Syracuse University that say the Justice Department declined to prosecute 62 percent of Indian Country crimes between 2004 and 2007. That includes 50 percent of reservation murders, 72 percent of child sex crimes, and 76 percent of adult rapes.

Wrigley defended the work of the department and said the data would not paint an accurate picture of their work because crimes in Indian country are often tracked differently from other crimes.

"Indeed such publication would simply create fodder for false comparisons that would inevitably prove corrosive," Wrigley said.

Dorgan said previous congressional testimony has shown that Native Americancrimes are low priority in some prosecutors' offices.

"Unfortunately, some offices have taken an out of sight, out of mind attitude with regard to our obligation in Indian Country," he said, calling the system "a proven failure."

Dorgan recently introduced a bill that would aim to fight high crime levels on American Indian reservations by boosting tribal law enforcement and improving coordination between federal and local authorities.