More than half of all violent crimes committed in the United States in 2000 were never reported to police, often because the victim felt it was a private matter or the injuries were not significant, government figures released yesterday show.

About 49 percent of the 6.2 million rapes, armed robberies and assaults were reported to police in 2000, according to the Justice Department. Armed robbery was the most likely to be reported, simple assault the least likely.

Crime victims most often cited "a personal matter" as the reason for not reporting a crime, particularly rapes and simple assaults. About 17 percent said they did not tell police because it was not important enough, while 14 percent said they told someone else such as a school principal or business associate.

About 5 percent said they feared reprisals, a number that rose to 12 percent for victims who decided not to disclose sexual assaults.

Susan Herman, executive director of the National Center for Victims of Crime, said many people are frightened that the offender might return if they go to the police. In some cases, a perpetrator they know has threatened more harm if they speak up, she said.

The Bureau of Justice Statistics report found that police were more likely to be told about crimes committed by strangers than by acquaintances, and people were less inclined to report armed robbery if the offender was believed to be a gang member.

Victims who were injured usually reported the crime, including 90 percent of gunshot victims. Women and older people more frequently reported crimes to police than did men and younger people.

James Lynch, law professor at American University's Department of Justice, Law and Society, said the new report does not address situations in which the victim might be partly to blame. "You're not going to call the police if you started it, and you lost," he said.

People also are frequently reluctant to tell police if a family member committed the crime, Lynch added, "figuring that you can get even later." If the crime was committed by the family's main breadwinner, he added, it could hurt the whole family if that person were jailed.

People who did report violent crimes most often said they did so to prevent future violence, stop the offender or protect others. About 8 percent said they called the police because they wanted to punish the offender, a number that rose to 12 percent for victims of sexual assaults.

The results are based on interviews of more than 872,000 people age 12 or older who were crime victims between 1992 and 2000. The report found that reporting of violent crime has risen from an average of 43 percent from 1992 to 1999, to 49 percent in 2000.

Counting property crimes such as theft and burglary, about 39 percent of the estimated 25 million total offenses committed in 2000 were reported to police. Car thefts and attempted thefts were reported about 81 percent of the time, while people who had their pockets picked told police in only about 28 percent of cases. The report also found that:

* Victims reported just over half of violent crimes known to police. Bystanders, relatives, officials at schools and other institutions and police officers also frequently reported the crimes.

* About 49 percent of violence against black people was brought to police attention, compared with 42 percent for white people and 40 percent for Asians. About 44 percent of violent crime against Hispanics was reported.