By THE ASSOCIATED PRESS

PLAINFIELD, N.J. (AP) — A federal lawsuit challenging the right of landlords to rent to illegal immigrants has stoked tensions over immigration that have been rising for years here.

A group opposed to illegal immigration filed suit against a Plainfield property management company this month, seeking to set a legal precedent by using a federal law normally employed against racketeers to punish landlords who rent to illegal immigrants.

The lawsuit accuses the company, Connolly Properties, of allowing so many undocumented tenants to live in its buildings that it amounted to unlawful harboring and should be considered a criminal enterprise that encouraged illegal immigration.

The suit was brought by the Immigration Reform Law Institute in Washington — the legal arm of the Federation for American Immigration Reform. The institute previously supported ordinances in Hazelton, Pa., and Riverside, N.J., that tried to punish landlords who rented to illegal immigrants or businesses that hired them.

A judge overturned the Hazelton ordinance, ruling it unconstitutional, and Riverside rescinded its ordinance, with officials saying the town could not afford the legal costs of defending it.

Flor Gonzalez, head of the Latin American Coalition in Plainfield, worries that her city may become the latest battleground in the nationwide debate over immigration.

She says that tensions over the city’s large immigrant population have been rising, with a recent series of beatings and robberies of immigrants, raids by federal immigration officials and ticketing of day laborers by the police.

“This is the worst it’s been. There is a lot of unfriendliness and disrespect against immigrants, and a lot has been happening quietly,” Ms. Gonzalez said. “We need big help in this town.”

Plainfield’s mayor, Sharon M. Robinson-Briggs said that she was not familiar with the details of the lawsuit, but added that immigrants deserved respect, regardless of their status.

“All our residents deserve to be treated fairly and equitably, whether they are born here or not,” she said.

The lawsuit was filed against Connolly Properties on behalf of a former Connolly employee and two tenants who are American citizens. The tenants charge that they were steered into buildings occupied by illegal immigrants who were too afraid about their legal status to complain about decrepit conditions, according to Michael M. Hethmon, a lawyer for the Reform Law Institute.

Connolly Properties has several rental complexes in northern New Jersey and Allentown, Pa.

Ron Simoncini, a spokesman for Connolly, said executives were bewildered as to why the company had become the target of the suit, which was filed under the Racketeer Influenced and Corrupt Organizations Act, known as RICO.

He added that he could not comment further before the company filed a response to the suit.

Mr. Hethmon said his group decided to take the case as part of its strategy of “attrition through enforcement,” or urging illegal immigrants to leave the country by making it more difficult for them to find employment and housing.

“We have felt for a long time that the racketeering statute would be useful in dealing with situations where businesses and commercial enterprises were heavily involved with illegal immigration,” Mr. Hethmon said.

“We’ve also felt that individual citizens, communities, neighborhoods and law-abiding small businesses have always needed tools with which they can defend themselves against the harmful effects of illegal immigration.”

Using anti-racketeering laws to prosecute landlords is a strategy that immigration experts say they expect to be tried in other parts of the nation.

“I think it’s a new tactic, because some of the other things haven’t worked,” said Donald W. Benson, a lawyer in the Atlanta office of the San Francisco labor law firm Littler Mendelson.

“Congress couldn’t reach a consensus to reform the immigration laws, states are trying to fill in the gaps and they’re having varied success, and local groups are trying to work through local ordinances, so it’s just one part of a much bigger picture of immigration struggles in the U.S.,” he said.

“I have no idea why they picked Plainfield,” said Christian Estevez, a member of the Plainfield school board who also sits on Gov. Jon S. Corzine’s panel on immigrant policy.

“This has caught us by surprise.”

Mr. Estevez said that he and other Plainfield residents were contacting national immigration advocacy groups for help.

According to the 2000 census, Plainfield, a city of some 50,000 people, is about 60 percent black, with the remainder roughly split between white and Hispanic.

In the past decade, Ms. Gonzalez said there had been a large influx of Hispanic immigrants, mostly from Central America.

The Plainfield City Council president, Harold Gibson, said he was unaware of the lawsuit, but that city officials had been trying to address concerns over immigration.

He cited the city’s efforts to find a solution to the day laborer situation that respected the laborers’ right to look for work while addressing community concerns.

“I think that the people in Plainfield, in terms of the City Council and the general population, they frown on illegal immigration, they don’t want undocumented persons living in the town, generally speaking,” he said.

“However, my position is that I don’t think we should set ourselves up as an immigration authority in terms of people who come from other countries and work hard to better themselves and help their families.”