Privacy groups, the Electronic Privacy Information Center (EPIC) and the Center for Digital Democracy (CDD), have approached the US Federal Trade Commission (FTC) to hold the Facebook’s $19 billion acquisition of WhatsApp, until privacy concerns are worked out.

The two privacy groups filed a formal complaint with the FTC that WhatsApp’s privacy policy is incompatible with Facebook’s. The complaint asks the regulators to investigate the deal “specifically with regard to the ability of Facebook to access WhatsApp’s store of user mobile phone numbers and metadata.”

“Acting in reliance on WhatsApp representations, Internet users provided detailed personal information to the company including private text to close friends. Facebook routinely makes use of user information for advertising purposes and has made clear that it intends to incorporate the data of WhatsApp users into the user profiling business model,” read the filing.

“The proposed acquisition will therefore violate WhatsApp users’ understanding of their exposure to online advertising and constitutes an unfair and deceptive trade practice, subject to investigation by the Federal Trade Commission.”

According to the complaint, WhatsApp has a “strong commitment to user privacy,” whereas Facebook’s current service compiles “virtually all available user data.”

The complaint also stated that the proposed merger violates the consent decree issued by the FTC in 2011. Facebook is under a 20-year privacy settlement with the FTC that requires the social network to seek permission from users before changing the way their personal information is released.

Facebook spokesperson said in response to the filing, “As we have said repeatedly, WhatsApp will operate as a separate company and will honor its commitments to privacy and security.”

The complaint noted that data protection authorities in European countries have already begun investigations on this acquisition and concluded demanding that the FTC to block the acquisition or “insulate” the WhatsApp’s users from Facebook data collection.