The move on Thursday was part of an agreement with 49 state attorneys general to increase the level of protection for the site's younger users.
The company also agreed to join MySpace on the Internet Safety Task Force, which MySpace established in its agreement with state attorneys general. The task-force agreement calls for the social networking sites to establish "age locking" around the profiles of users younger than 18.
In September 2007, New York Attorney General Andrew Cuomo threatened to subpoena Facebook after investigators posing as underage users were sexually solicited by adults.
Facebook agreed to enhance its age and identity identification tools, issue automatic warning messages when children attempt to give personal information to unknown adults, restrict users' ability to change their listed ages and immediately sever links to pornographic websites.
The deal also calls for Facebook, which has about 47 million users, to allow someone independent, and approved by Cuomo's office, to report on its compliance with the new safeguards for two years.