The additional safety measures on Thursday follow a similar agreement in January with larger rival MySpace.

Facebook said it would focus on improving the technology it employs to weed out inappropriate online behaviour, and to make it tougher for adults to make friends with minors.

The agreement reflects Facebook's commitment to 'keeping kids safe online', said Mr Chris Kelly, the Palo Alto-based company's chief privacy officer.

Both the Facebook and MySpace agreements came in response to calls last year from the attorneys general to improve online safeguards.

The millions of youngsters who share everything from music tastes to intimate details of their lives online have turned social networks into veritable hunting grounds for sexual predators.

Without checks, an adult can pose as a minor and lure a child into parting with information.

Last October, Facebook and New York Attorney-General Andrew Cuomo agreed to settle a child safety probe after undercover tests on the social network's safety controls and procedures showed lapses.

Investigators from Mr Cuomo's office posed as young teenagers on Facebook and received sexual advances from adults within days. Complaints by investigators posing as parents were not immediately addressed, Mr Cuomo's office said.

Facebook then agreed to begin addressing within 24 hours any complaint about inappropriate content and allow an independent examiner to oversee how it handles the complaints.

The website is now taking several steps to ensure safety, including 'age-locking' of profiles of under-18 members, Mr Kelly said.

'If people try to change their ages, it will be specifically reviewed,' he said.

Another safety feature sends automatic warning messages when a child is at risk of revealing personal information to an unknown adult.

Facebook also said it would immediately remove user groups dedicated to incest, paedophilia and cyber-bullying, and remove links to pornographic materials from its website.

MySpace, whose January agreement with 49 attorneys general also took steps to allow minors to keep their profiles 'private', was subject to a 2006 lawsuit by a 14-year-old girl, who said she was sexually assaulted by a 19-year-old man she met on the site.

Last July, MySpace, which News Corp bought in 2005 for US$580 million (S$795 million), said it had deleted 29,000 convicted sex offenders from its site.

Facebook, which says it has more than 70 million active members, was started by Mr Mark Zuckerberg in 2004 as a socialising site for fellow Harvard University students. It has since opened its membership to anyone over 13 years of age with an e-mail address.

More than half of Facebook's members have graduated from college, and the fastest growing demographic is 25 years and up, Mr Kelly said.

He also said Facebook is part of an Internet Task Force set up in January, when the MySpace agreement was signed, that is working on the feasibility of online verification technology. -- REUTERS