Top federal officials pushed forward Wednesday on efforts to establish mandates for Internet privacy.

In a Senate hearing on Internet privacy, the chairman of the Federal Trade Commission reiterated his push for a Do Not Track tool to help protect Internet users’ privacy, saying consumers should have the choice to have their activity followed online. The Obama administration also threw its support behind legislation that would strengthen privacy protections on the Web.

The greater attention on online privacy reflects concerns by privacy advocates and civil liberties groups that companies such as Facebook and Apple are encouraging users to share greater information about themselves and their Internet activities on their applications. Those companies are quickly gaining more users, but federal laws have not kept up with the applications to ensure that personal information isn’t being improperly used.

FTC Chairman Jon Leibowitz, said several companies such as Microsoft and Mozilla have done a good job of putting tools on their browsers to allow users to voluntarily opt out of being tracked on the Web. But he said that without “baseline privacy protections” across the Web industry, consumers will face a patchwork of privacy policies that could differ Web site by Web site.

For that reason, Leibowitz said, he supports a so-called Do Not Track mechanism, a universal opt-out tool -- perhaps on a Web browser -- that would allow users to stop advertisers and Web sites from following their activity on the Web. Companies track individual users to tailor advertising, among other practices that worry privacy advocates.

“Do Not Track is no longer just a concept. It is becoming a reality,” Leibowitz said at the hearing before the Senate Commerce Committee. “An effective Do Not Track system would go beyond simply opting consumers out of receiving targeted advertisements. It would opt them out of having their behavior tracked online.”

He said the agency is also focusing on how consumer privacy is handled on mobile devices. One company the FTC is investigating has a terms-of-service page that takes 152 clicks from a mobile device to access information on the company’s privacy policy, Leibowitz said.

Lawrence Strickling, head of the National Telecommunications & Information Administration, said the Obama administration supports laws to create basic standards for privacy protections. He didn’t provide details on what those standards would include. But Strickling, the administration’s chief tech policy adviser, said the FTC would be empowered to enforce a privacy law. The NTIA has not specifically endorsed the FTC’s recommendation for a universal Do Not Track tool.

In Congress, Sen. John Kerry (D-Mass.) is expected to introduce a privacy bill soon, and similar legislative efforts are underway in the House.

Consumer advocacy groups lauded the moves by federal officials.

“There is a window of opportunity here to pass strong consumer privacy legislation — with bipartisan support — in the 112th Congress,” Justin Brookman, a privacy project director at the Center for Democracy & Technology, said in a statement. “The administration’s support is a welcome addition to that debate.”