NEW YORK — An organization of Internet advertisers took steps this week to protect Web surfers' privacy, but the system may be more bark than bite.

Third-party advertisers regularly use information gathered from your browsing and buying habits to target you with relevant ads — think, for instance, of how many times you've visited an online retailer, then noticed the retailer's banner ads following you around the Internet. That's raised some privacy concerns among many users uncomfortable with advertisers knowing their habits in such detail.

A feature for protecting internet users' privacy has gone into effect, but critics say it's ineffective.

The Interactive Advertising Bureau, whose members are responsible for 86% of online advertising, has proposed a self-regulatory step in which advertisements would contain a "do not track" button as a means of disclosing the tracking mechanism and giving users the ability to opt out. Monday was the deadline for the members to join the program and comply with the rules.

Privacy advocates aren't convinced, however.

The advocacy group Consumer Watchdog said Monday that the "Advertising Option Icon" doesn't qualify as a "do not track" feature, as it allows users only to opt out of being tracked by the companies participating in the program. Also of concern was the fact that the opt-out action would remain in place only until the user cleared his or her tracking cookies — something many privacy-conscious people do on a regular basis.

Perhaps the biggest objection, though, is that any self-regulating system will be ineffective in the absence of actual government enforcement.

"This industry program is another example of the failure of self-regulation to protect consumers from unwanted monitoring of every move they make on the internet and their mobile devices," said Carmen Balber, Washington director for Consumer Watchdog, in a statement. "Action by Congress and the FTC to require a 'Do Not Track Me' option is crucial for consumers to gain control over their own information."

It's not the first time we've heard that refrain in reference to Internet tracking. Earlier this year, when Microsoft's (MSFT) Internet Explorer joined Mozilla's Firefox in implementing a tool that would let users automatically disable tracking, we noted that both browsers rely on voluntary compliance by the advertisers.

The question, then, is whether such mandatory compliance will take place. When the Federal Trade Commission proposed a "do not track" option back in December, it said self-regulation could be sufficient. But its tune may be changing: Earlier this month, an FTC commissioner expressed his belief that more compulsory regulations may be necessary to force advertising companies to disclose their practices and give consumers a way to opt out.

If the industry's new attempt at self-regulation does indeed prove ineffective, those calls could grow louder.