Fast-growing U.S. social network Web site Facebook said on Friday it has adopted new privacy controls following an unprecedented online backlash over a new feature that let users track their friends online.

Facebook, which started as an online meeting place among college students but opened to all ages recently, said it now will let its 9.5 million users control what and how much information is shared with friends on the network.

We really messed this one up, Facebook founder and CEO Mark Zuckerberg said in statement to members on the site. We did a bad job of explaining what the new features were and an even worse job of giving you control of them, he said.

The outcry began on Tuesday when the site introduced News Feed, a feature which instantly notified users of friends' activities on the network, including who they contacted and how they changed their profiles. A second change, called Mini-Feed, highlights changes on each individual's profile.

In protest, 700,000 Facebook members signed an online petition opposing the changes this week. The outcry took on the trappings of a political movement on college campuses, among a generation not known for its social activism.

Protest organizers responded to Facebook's new privacy protections by saying they addressed most of their basic complaints and they were happy that Facebook had listened.

This group has decided it's not going to declare victory, because there was not a loser, nor was there a winner, Students Against the Facebook News Feed, said in a statement. We made our voices heard and Facebook listened.

If the new privacy options do not indeed go all the way, do what you did before: complain, the group cautioned.

The stepped-up privacy controls now let users block information on the News Feed and Mini-Feed features, as well as a setting to remove the time-stamp of postings, responding to complaints that such features were creepy and big Brotherish in that they helped users spy on their friends activities.

We didn't build in the proper privacy controls right away. This was a big mistake on our part, and I'm sorry for it, Zuckerberg said.

Facebook, the No. 2 social network behind News Corp.'s, had been lauded for its privacy protections until the new features were announced.

The online protests took place largely within the confines of the Facebook site itself. Outrage over the features was balanced by a general defense of Facebook as an institution. Some users also leapt to the site's defense, creating groups like Against Being Against the News Feed.

My goal is to slowly return to normality, said sudden celebrity Benjamin Parr, a student at Northwestern University in Chicago, who created Students Against the Facebook News Feed online petition on a whim Tuesday morning.

Now maybe we could start standing together in other areas, ones that I am sorry to say are a lot more pressing than Facebook, wrote Brandon Nyman, a collaborator with Parr on the petition site, who is a student at Illinois State. Nyman pointed to issues like war, hunger, AIDS, or others.

Igor Hiller, 17, who lives in Palo Alto, California, where Facebook is headquartered, said he was canceling plans to hold a protest outside the company's headquarters on Monday. We really don't see the need to anymore, he said by phone.

They listened. We got really what we wanted: You can opt out of News Feed, Hiller said. Instead, he said he may organize a rally thanking Facebook for responding so quickly.

(Additional reporting by Kenneth Li in New York)