Facebook, which has over 30 millions users in Britain, argues it is offering more choice to tech-savvy teenagers.
It also stressed that initial privacy settings for teens under 18 would automatically be programmed so posts are seen only by friends.
"We take the safety of teens very seriously, so they will see an extra reminder before they can share publicly," the company headed by Mark Zukerburg said in its update.
It already announced last week that it is removing privacy setting so that anyone can search for a user's profile.
Children's groups and internet safety experts denounced the move, saying it could leave young people more vulnerable to cyber-bullying.
Anthony Smythe, managing director of BeatBullying, told The Times:
Facebook is facing a backlash from campaigners after announcing it will allow millions of teenagers to open up their profiles to strangers.
The social networking site announced that users aged from 13 to 17 will now be able to switch their settings to share posts with anyone on the internet, rather than just their "friends" or "friends of friends".
Privacy lawyer Gerald Shamash has told the Guardian that the allegations a Virgin Atlantic employee passed on information about eight celebrities is "extremely worrying" and "this could be the tip of the iceberg".
Mr Shamash also said advance knowledge of the whereabouts of celebrities was the "bread and butter" of life as a picture agency or tabloid newspaper.
Reacting to the allegations that an employee at Virgin Atlantic passed the flight details of eight celebrities including the footballer Jermaine Defoe to a paparazzi agency, a spokeswoman for the footballer said:
"This is a serious breach of privacy. We'll be consulting with our lawyers and investigating the matter further."
Virgin Atlantic sources told The Guardian that four of the eight celebrities whose flight details were allegedly leaked to a paparazzi firm, flew on the dates given by the airline employee.
Ashley Cole and Sienna Miller were pictured in Heathrow and Los Angeles respectively, on the dates allegedly provided. The other four celebrities are believed to have cancelled their flights.
A Virgin Atlantic employee has quit after allegedly passing on eight celebrities details to a global paparazzi firm, according to The Guardian.
The celebrities included actresses Sienna Miller and Gwyneth Paltrow, footballer Ashley Cole and his former wife and singer Cheryl.
Virgin Atlantic said they are "deeply concerned" by reports that eight celebrities flight details may have been passed on to a paparazzi agency by a former employee.