Hartford, Conn. ? Facebook, the world’s second-largest social networking Web site, is adding more than 40 new safeguards to protect young users from sexual predators and cyberbullies under an agreement with officials nationwide that was announced Thursday.

The measures include banning convicted sex offenders from the site, limiting older users’ ability to contact subscribers under 18 and participating in a task force set up in January to find ways to verify users’ ages and identities.

“The agreement marks another watershed step toward social networking safety, protecting kids from online predators and inappropriate content,” said Connecticut Attorney General Richard Blumenthal, who announced the agreement Thursday with his counterparts in other states.

Officials from Washington, D.C., and 49 states have signed on.

Facebook, which has more than 70 million active users worldwide, already has enacted many of the changes and others are in the works, its officials said Thursday.

“Building a safe and trusted online experience has been part of Facebook from its outset,” said Chris Kelly, Facebook’s chief privacy officer. “The attorneys general have shown great leadership in helping to address the critical issue of Internet safety, and we commend them for continuing to set high standards for all players in the online arena.”

Texas did not endorse the agreement or a similar one reached in January among the other states, the District of Columbia and MySpace, the world’s largest online social network with 200 million users worldwide.

Texas officials say they want the sites to work faster on verifying users’ ages and identities.

The attorneys general have been negotiating for months with Palo Alto, Calif.-based Facebook.

“Social networks that encourage kids to come to their sites have a responsibility to keep those kids safe,” North Carolina Attorney General Roy Cooper said. “We’ve now gotten the two largest social networking sites to agree to take significant steps to protect children from predators and pornography.”

MySpace, Facebook and other online networks have created a new venue where sexual predators could lie about their age to lure young victims to chat, share images and sometimes meet in person, law enforcement officials said.

The networks also have empowered cyberbullies, who have sent threatening and anonymous messages to classmates, acquaintances and other users.

John Palfrey, executive director of the Berkman Center for Internet and Society at Harvard University, said research shows online bullies are far more common than sexual predators.

“It’s very rare for an adult to meet a child on a social network and to do them harm, although the ones that do occur get a huge amount of attention, and they are terrible,” he said.

Online bullying, whether through instant-message programs or social networks, is on the rise, he said.

The issue has gained national attention after recent high-profile cases, including the 2006 suicide of a 13-year-old Missouri girl who was victimized by an Internet ruse. Megan Meier hanged herself after receiving nasty online comments from a MySpace friend who turned out to be fictional, invented by two acquaintances and the mother of one of those girls.

Other children have been the subjects of harassment campaigns, including whole sites set up to deride them.

“What’s going on online is not much different than bullying on the playground,” Palfrey said. “It just happens to be playing out in public spaces where kids are spending a lot of time online.”

Facebook lets users block online bullies and others from contacting them. They also can conceal their “online now” status and use privacy controls to limit who can view their images and other measures.