Arizona's new crackdown on illegal immigration will increase crime in U.S. cities, not reduce it, by driving a wedge between police and immigrant communities, police chiefs from several of the state's and the nation's largest cities said Tuesday.

The new Arizona law will intimidate crime victims and witnesses who are illegal immigrants and divert police from investigating more serious crimes, chiefs from Los Angeles, Houston and Philadelphia said. They will join their counterparts from Montgomery County and a half-dozen other U.S. cities in meeting Attorney General Eric Holder on Wednesday morning to discuss the measure.

"This is not a law that increases public safety. This is a bill that makes it much harder for us to do our jobs," Los Angeles Police Chief Charlie Beck said. "Crime will go up if this becomes law in Arizona or in any other state."

The delegation was organized by the Police Executive Research Forum, a membership organization of police chiefs that functions as an independent think tank in Washington. The group's meeting with Holder comes as 15 states are considering their own versions of the Arizona law, which defines illegal immigration as criminal trespassing and requires police to request documents of anyone they stop and have a "reasonable suspicion" is in the country illegally.

Several recent public opinion polls indicate that as many as 70 percent of Americans surveyed support such a police requirement.

The American Civil Liberties Union, Mexican American Legal Defense and Educational Fund and other civil rights groups have filed lawsuits to block the Arizona law, arguing that the Constitution preempts states from enforcing federal law and that the measure will lead to racial profiling.

The U.S. Justice Department, which Holder heads, is also weighing whether to file suit or intervene.

Although the ranks of chiefs appealing to Holder included Arizonans Jack Harris of Phoenix, Roberto Villasenor of Tucson and John Harris of Sahuarita, president of the Arizona Association of Chiefs of Police, law enforcement opinion in the state is deeply split.

One of the new law's most prominent backers is Maricopa County Sheriff Joe Arpaio. His suburban Phoenix county has caught 120,000 illegal immigrants under a separate federal program that deputizes state and local law enforcement agents to catch illegal immigrants under limited circumstances, mostly after they have been booked into local jails.

Pinal County Sheriff Paul Babeu, head of the Arizona Sheriff's Association, is another backer.

Babeu called the police chiefs' argument "flawed from the beginning." Cooperation from illegal immigrants, particularly those coming from Mexico, is already low, he said, because they are in the United States illegally and because of law enforcement corruption in their native countries.

"Somehow when they appear in the U.S., magically their perception of law enforcement improves overnight?" Babeu said.

"The people of Arizona believe the overall majority of Americans are not only supportive of this law, but that our measure of generosity has been crossed, a line has been crossed," Babeu added.

Unlike most police chiefs, almost all sheriffs are elected officials. However, only about 60 of the nation's 3,000-plus elected sheriffs have chosen to participate in the federal program championed by Arpaio. Meanwhile, the nation's leading police chiefs have voiced caution about such initiatives.

In 2006, the Major Cities Chiefs Association - which represents 56 U.S. cities - unanimously warned that putting "local police in the crosshairs" of the national immigration debate would undo the success of community policing efforts in recent decades, said San Jose, Calif., Police Chief Rob Davis, association president and part of the group meeting Holder.

Requiring the Los Angeles Police Department to prioritize the arrest of 400,000 illegal immigrants among the city's 4.1 million residents would "cripple us and make it impossible for us to do our jobs," Beck said.

Harris of Phoenix said he feared the Arizona measure will become a political fad at the state level, leading federal officials to neglect a national solution to core issues of illegal immigration.

"We understand and agree: Federal immigration law, the whole system, is broken, and that people are very, very frustrated all across this country," Harris said. "But this state law doesn't solve the immigration problems for the country. The solution is here in Washington, D.C., and Congress must step forward and come up with a comprehensive immigration reform that will really solve the problem."