According to a Consumer Reports survey, as many as 7.5 million children under the age of 13 have accounts on Facebook, a violation of the social networking site's policy that enables it to operate without having to comply with regulations governing children online.

Rockefeller questioned whether Mark Zuckerberg, co-founder of Facebook, had any “social values. It's my general feeling that people who are 20, 21, 22 years old really don't have any social values at this point”, he was quoted as saying by the Los Angeles Times.

Facebook chief technology officer Bret Taylor responded that his company shuts down the accounts of people found to be lying about their age, but he admitted that the company primarily depends on other users to report violations, the newspaper reported.

Also testifying at the Senate hearing were representatives from Google and Apple, who were there to defend their companies against accusations that their smartphones track user location without the user’s permission. Both companies denied the accusations at the hearing.

“Apple provides easy-to-use tools that allow our consumers to control the collection and use of location data on all our mobile devices. Apple does not track users’ locations – Apple has never done so and has no plans to ever do so”, testified Catherine Novelli, vice president of worldwide government affairs at Apple.

Added Alan Davidson, director of public policy for the Americas at Google: “location sharing on Android devices is strictly opt-in for our users, with clear notice and control.”

Both firms pledged their companies’ commitment to user privacy. Davidson said that Google’s business “depends on protecting the privacy and security of our users. Without the trust of our users, they will simply switch to competing services, which are always just one click away.” Novelli stressed that “Apple is deeply committed to protecting the privacy of our customers who use Apple mobile devices, including iPhone, iPad and iPod touch.”

Rockefeller, who is chairman of the powerful Commerce, Science and Transportation Committee, questioned whether the companies were actually committed to privacy. “I think anyone who uses a mobile device has an expectation of privacy, and sadly that expectation is not always being met.”

The senator also noted the prevalence of tracking online behavior in order to provide that information to third-party advertisers. “These third parties may use this information to target advertising at the individual or to compile a comprehensive profile of the individual based on a broad range of online and offline activities.” Rockefeller has introduced legislation that would force companies to enable consumers to opt out of online tracking.