Facebook founder and CEO Mark Zuckerberg has personally apologised on the social-networking site's blog over the "Beacon" fiasco.

The new "Beacon" system, is a controversial new advertising program that flags user's retail purchases in Facebook's news feeds has been the target of mass protest from consumer groups.

More than 50,000 people signed a petition on US site MoveOn.org demanding the site made changes to the Beacon feature.

Facebook has u-turned on the feature and has said it will allow members to permanently shut off Beacon.

"We've made a lot of mistakes building this feature, but we've made even more with how we've handled them", Zuckerberg said, acknowledging it took Facebook too long to respond to complaints.

"We simply did a bad job with this release, and I apologize for it."