Facebook’s acquisition of messaging application WhatsApp was approved by the Federal Trade Commission late last week, but not without a stern notice from the agency, which warned that it would be keeping a watchful eye on the two companies going forward.

In a letter addressed to officials at Facebook and WhatsApp on Thursday, the FTC’s Bureau of Consumer Protection Director Jessica Rich made it clear that the agency would continue to ensure the companies honor their promises to users.

“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,” Rich wrote. “We want to make clear that, regardless of the acquisition, WhatsApp must continue to honor these promises to consumers.”

The privacy policy for WhatsApp, the popular app that allegedly sends 50 billion messages between users daily, states that user information will not be used for advertising purposes and won’t be sold to a third party. The FTC’s letter (.PDF) claims this is something that shouldn’t be nullified by the Facebook purchase. The FTC adds that if Facebook were to go ahead and share any of its newly acquired WhatsApp information, it would violate its privacy promises, not to mention an order the agency has placed on the social network.

That order basically makes sure Facebook doesn’t misrepresent the way it handles users’ privacy or the security of consumers’ personal information.

The letter, which was addressed to Facebook’s Chief Privacy Officer Erin Egan and WhatsApp’s General Counsel Anne Hoge, goes on to state that data collecting changes could be made as long as they get users’ “affirmative consent.” If users don’t agree with new procedures they should be granted the opportunity to opt out or at least understand “that they have an opportunity to stop using the WhatsApp service.”

“Failure to take these steps could constitute a violation of Section 5 and/or the FTC’s order against Facebook,” the letter states.

When the $19 billion acquisition was first announced in February, privacy advocates were rattled that Facebook would be able to mine WhatsApp’s vast reservoir of user information and convert that into ad revenue without the users’ consent.

Organizations such as the Center for Digital Democracy (CDD) and the Electronic Privacy Information Center (EPIC) both decried the move in March, requesting the FTC look into it. Jan Koum, WhatsApp’s founder later responded with a blog post, “Setting the record straight,” that insisted both firms would “remain autonomous and operate independently.”

*Photo via alvy‘s Flickr photostream, Creative Commons

Categories: Mobile Security, Privacy