San Francisco ? A year after goading MySpace.com into overhauling its safety practices, state law enforcement officials Monday stepped up their criticism of how social network Facebook Inc. protects its users from sexual predators.

New York Attorney General Andrew Cuomo said his office was investigating whether Facebook made false claims about the safety of its social network. He issued subpoenas to gather more information about the Palo Alto company’s policies and procedures after an undercover investigation found that Facebook.com was slow to respond to complaints about sexual solicitations of underage users.

“It does not have the right to represent that its site is safe and that it promptly responds to complaints when such statements are not accurate,” Cuomo said.

Safety concerns could dog Facebook, which has soared to become the No. 2 social networking site, much as they have its bigger rival, MySpace. Facebook has become one of Silicon Valley’s hottest companies, poaching employees from such powerhouses as Google Inc. and attracting advertisers eager to get their messages in front of the site’s 42 million registered users.

Facebook spokeswoman Brandee Barker released a statement saying the privately held company took the concerns “very seriously” and pledged to work with Cuomo and other state attorneys general.

But one prominent Internet safety advocate came to Facebook’s defense.

Parry Aftab, a New York lawyer who is executive director of wiredsafety.org, said Facebook had been a model corporate citizen since she began working with the site in 2005.

Facebook chief privacy officer Chris Kelly, a legal veteran in the privacy arena, is “outrageously responsive” to complaints from watchdog groups and ahead of the curve in setting up procedures and training monitors, Aftab said.

Connecticut Attorney General Richard Blumenthal and North Carolina Attorney General Roy Cooper said Monday they were heading up a 50-state investigation into Facebook. Both met with Facebook representatives last week.

“Facebook has a long way to go before we are satisfied,” Blumenthal said.

Attorneys general from a growing number of states are pushing for state and federal laws to require social networking sites to verify ages and identities or to get parental consent before allowing underage users to join.

A spokesman for California Attorney General Jerry Brown said investigators routinely conduct undercover sting operations to catch sexual predators, but he would not say if the office was scrutinizing the safety procedures of Facebook or other social networking sites.

Facebook once catered exclusively to college students but in recent years opened its site to the general public. Its traffic soared to 19.2 million visitors in August, a 117 percent jump from 8.9 million a year before, according to Nielsen/NetRatings. The growth rate for teens ages 12-17 has been even higher at 122 percent .

To conduct its sting, Cuomo’s office set up several Facebook accounts, posing as 12- to 14-year-old users. Within days, the fake users received several sexual solicitations from adults. Cuomo says the company ignored complaints about the inappropriate contact.