New York City prosecutors on Tuesday endorsed the United States' first proposed law to ban registered sex offenders from social networking sites like Facebook and MySpace, officials said. The proposal would ban thousands of the state's sex offenders from communicating with minors online. The law would force sexual predators to register their instant messaging screen names and enable sites like MySpace and Facebook to block their access.

MySpace came under state legal scrutiny after some youth members fell prey to adult predators posing as minors.

Last month, MySpace and 49 U.S. state attorneys general agreed on a broad set of guidelines for protecting youths, including developing an e-mail registry that would allow parents to prohibit their children from creating an online profile for the network.

Facebook, a privately held smaller rival, in October promised to address within 24 hours any complaint about inappropriate content and allow an independent examiner to oversee how it handles complaints.