Federal Communication Commission Chairman Tom Wheeler (Brendan Smialowski/AFP, file)

The Federal Communications Commission said Friday that it will not seek to impose a requirement on Google, Facebook and other Internet companies that would make it harder for them to track consumers’ online activities.

The announcement is a blow to privacy advocates who had petitioned the agency for stronger Internet privacy rules. But it's a win for many Silicon Valley companies whose business models rely on monetizing Internet users’ personal data.

It's also the latest move in an ongoing battle to defend the agency’s new net neutrality rules, which opponents warned would result in the regulation of popular Web sites and online services. By rejecting the petition, the FCC likely hopes to defuse that argument. The rules, which took effect this summer, allow the FCC to regulate only providers of Internet access, not individual Web sites, said a senior agency official.

Consumer Watchdog, an activist group, petitioned the FCC in June to support a technology that would allow consumers to signal to Web sites that they did not want to be tracked. By clicking a button in their browser settings, users would have been able to send a “do not track” message to Web site operators when they surfed the Internet.

Some Web sites have committed to honoring those requests voluntarily, but many do not. If it had succeeded, the petition could have made Do Not Track a U.S. standard.

In a sign of its growing ambitions, however, the FCC has dramatically expanded its role in combating privacy violations among communications providers. Agency officials slapped Cox Communications, the country’s fourth-largest cable Internet company, with a $595,000 fine Thursday to settle charges related to a breach of consumer data. It has also gone after AT&T and a number of smaller telecom companies for similar security breaches.

Although the agency appears to be stopping short of establishing privacy rules for Web site operators, it is studying how net neutrality could allow it to set new privacy expectations for Internet providers.

Outside attempts by industry and privacy advocates to define and enforce a Do Not Track standard have been plagued by delays, as well as debates over what such a signal would require.

Privacy groups argue that Do Not Track should mean that no information is collected about a user. Online advertising groups say Do Not Track should prevent a company from serving up targeted advertisements but not impede data collection. This debate, however, has been superseded by even newer tracking technologies that Do Not Track is not designed to address.

The current Do Not Track proposal before the World Wide Web Consortium, an international Web standards body, has faced criticism from privacy advocates and leaders on Capitol Hill who say it does not do enough to protect consumers from companies that track users. In a letter to the group sent last month, Sens. Ed Markey (D-Mass.) and Al Franken (D-Minn.) and Rep. Joe Barton (R-Tex.) expressed concerns about the plan.

“Under the standard, first parties are free to continue tracking online activity even if a user activates the 'Do Not Track' signal and can share that information among its many affiliates,” the lawmakers wrote.