New privacy arrangements were introduced on December 9, with a pop-up message that asked users to update their privacy settings.
Facebook said the changes help members manage updates they wanted to share, not trick them into revealing too much.
"Facebook is nudging the settings toward the 'disclose everything' position," said Marc Rotenberg, executive director of the US Electronic Privacy Information Center (Epic). "That's not fair from the privacy perspective."
Epic said it was analysing the changes to see if they amounted to trickery.
In a statement, the Electronic Frontier Foundation said: "These new 'privacy' changes are clearly intended to push Facebook users to publicly share even more information than before. "
It added: "Even worse, the changes will actually reduce the amount of control that users have over some of their personal data."
Facebook began testing the privacy changes during mid-2009 before introducing them site-wide. The changes let people decide who should see updates, whether all 350 million Facebook members should see them, and if they should be viewable across the web.
Barry Schnitt, a Facebook spokesman, said users could avoid revealing some information to non-friends by leaving gender and location fields blank.
He said the changes to privacy made it easier to tune the audience for an update or status change so default settings of openness should have less impact.
Users of social networks are now splitting into two camps - what I would call the broadcasters and the whisperers - Rory Cellan-Jones, BBC technology correspondent
"Any suggestion that we're trying to trick them into something would work against any goal that we have," said Mr Schnitt.
Facebook would encourage people to be more open with their updates because, he said, that was in line with "the way the world is moving".
Assessing the changes, privacy campaigners criticised a decision to make Facebook users' gender and location viewable by everyone.
Jason Kincaid, writing on the Tech Crunch news blog, said some of the changes were made to make Facebook more palatable to search sites such as Bing and Google.
Blogger Marshall Kirkpatrick was worried that the default setting for privacy was to make everything visible to everyone.
"This is not what Facebook users signed up for," he wrote. "It's not about privacy at all, it's about increasing traffic and the visibility of activity on the site."
He also criticised the fact that the pop-up message that greets members asking them to change their privacy settings was different depending on how engaged that person was with Facebook.
He said Facebook was "maddeningly unclear" about the effect of the changes.
Many users have left comments on the official Facebook blog criticising the changes. Some said they had edited their profiles and reduced their use of the social site to hide information they do not want widely spread either by accident or design.