The overall 3.7 percent uptick in violent crime between January and June comes amid a still-incomplete Justice Department study of 18 cities for clues on why criminal activity is increasing.

Property crimes like auto theft and other larcenies were down by 2.6 percent over the same six-month period, the data show. But the number of arsons shot up by nearly 7 percent, the FBI reported.

If the numbers stay at the current pace, the rate of violent crime will increase in 2006 for the second year in a row. The FBI's 2005 annual report on violent crime showed that violent crimes increased in 2005 for the first time since 2001; the 2.3 percent increase was the largest jump since 1991. The US Justice Department has launched an investigation to examine why the violent crime rate has increased.

“This is a concern we’ve been focused on,” said Gene Voegtlin, legislative counsel for the International Association of Chiefs of Police, which represents an estimated 20,000 law enforcement officials and has been pushing for more crime-fighting funding. “A lot of (police) agencies are really stretched thin when it comes to the budget and their ability to aggressively combat crime.”

The Justice Department did not have an immediate comment.