Three convicted sex offenders have been charged with surfing MySpace and Facebook, the New Jersey Attorney General's Office announced yesterday.

The state police said they believe this is the first time anyone has been charged under a law adopted in January that makes it illegal for some registered sex offenders to use parts of the Internet. Violators can face up to 18 months in prison.

Authorities and the operators of the popular Web sites have been trying to scour them of predators. At least two other states, Nevada and Florida, have similar laws that make the sites off-limits to some sex offenders, and more states have considered following suit.

In Florida, sex offenders are required to register their e-mail and instant-messaging names with the state, which turns the information over to MySpace, Facebook, and other social-networking sites so they can block their access to those sites.

In the New Jersey case, State Police Lt. Joseph Furlong said Pietro Parisi, 24, of Westville; Felice Black, 24, of Paterson, and Stanton Ulmer, 32, of Neptune - did not seem to be behaving improperly online. "But they are not allowed to be on there doing anything," Furlong said.

Furlong said state troopers set up accounts as teenagers to monitor the sex offenders, but he would not elaborate on how they did that.

Authorities seized computers, a Web camera and a cell phone, and are determining what evidence might be on those devices.

The law restricts Internet use for anyone who used a computer to help commit the original sex crime, such as trying to lure a potential victim with electronic correspondence. The law also may be applied to paroled sex offenders under lifetime supervision, but exempts computer work done as part of a job or search for employment.

The state Parole Board last year adopted a rule prohibiting sex offenders under supervision from using the Internet to socialize or use social-networking sites.

All three of the men charged in New Jersey had underage victims in their original crimes and all are listed as moderate-risk sex offenders. Of the three, only Parisi is listed on the publicly available database of sex offenders.

None of the men could be reached for comment.

Furlong said each had admitted to maintaining an account on one of the sites even after being told by a parole officer that doing so was against the law and signing a paper to acknowledge that he understood.

The law and the investigation have roots in a civil investigation led by the Division of Consumer Affairs, which found last year that nearly 300 registered sex offenders in the state had accounts - under their own names - on the sites.

Investigators set up their own accounts so they could monitor those users. Over a few months, they saw many of their accounts be canceled or go dormant. But a few, Furlong said, were still actively used.

Ulmer served nearly four years of a 10-year sentence for a 1999 sexual assault of a girl. He has been out of prison since 2003.

Parisi was released from prison last year after serving more than four years for endangering the welfare of a child and sexual assault. According to the state's registry of offenders, the sex acts with the girls were consensual.

Black was released from prison last year after serving nearly three years for a litany of charges including drug possession, shoplifting, and endangering the welfare of a child.

The men were all released on their own recognizance. None, Furlong said, is considered to be a flight risk.