• by Wendy Davis  @wendyndavis, April 10, 2014

The Federal Trade Commission has approved Facebook's $19 billion acquisition of messaging service WhatsApp, but is warning the social networking service that it can't draw on data about WhatsApp's users for ad purposes without their explicit consent.

“WhatsApp has made a number of promises about the limited nature of the data it collects, maintains and shares with third parties -- promises that exceed the protections currently promised to Facebook users. We want to make clear that, regardless of the acquisition, WhatsApp must continue to honor these promises to consumers.” Bureau of Consumer Protection Director Jessica Rich wrote to the companies on Thursday.

Rich specifically calls the company's attention to promises by WhatsApp that users' information won't be used for advertising, or shared with third parties engaged in marketing, without their consent. “Facebook's purchase ofWhatsApp would not nullify these promises,” the letter states.

The FTC didn't state whether it had approved the deal, but Facebook responded to news of Rich's letter by announcing that the deal had been OK'd. “We're pleased the FTC has completed its review and cleared our acquisition of WhatsApp,” a spokesperson stated. “Naturally, both companies will continue to comply with all applicable laws after the transaction closes.”

Some privacy advocates who had raised concerns about the deal cheered news that the FTC had warned the companies. “The FTC is to be commended for sending a very strong signal that they will hold Facebook and WhatsApp accountable for their promises,” said Jeff Chester, executive director of the Center for Digital Democracy.

Earlier this year, that organization and the Electronic Privacy Information Center asked the FTC to investigate privacy issues raised by the acquisition.

Two years ago, Facebook settled an FTC complaint by promising obtain users' express consent before sharing their information more broadly than its privacy policy allowed when users uploaded the data. Rich reminded Facebook of that settlement in the letter, which noted that violations could result in chrages of $16,000 per instance.