Facebook has said it will buy messaging app WhatsApp for $19bn (£11.4bn) - the social networking giant's biggest purchase to date.
WhatsApp is popular with people looking to avoid text messaging charges and has been cited as a rival to BlackBerry Messenger.
WhatsApp has over 450 million monthly users.
In a statement, Facebook founder Mark Zuckerberg described WhatsApp's services as "incredibly valuable".
WhatsApp allows users to send messages over internet connections, avoiding text messaging fees. The company claims it is currently registering one million new users a day.
Facebook will pay $4bn in cash and $12bn in stock for the firm. An extra $3bn in restricted stock will be given to WhatsApp's founders and employees.
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The privacy advocates have asked regulators to investigate the deal, and possibly even block it, due to concerns over how the social network will use the personal data of WhatsApp's 450 million users.
EPIC and CDD's concerns are focused around the fact that WhatsApp, a service that allows mobile users to send each other messages, had built up a solid reputation for not collecting user data for advertising purposes.
In fact, the service built its popularity on the back of a policy of only saving unsent messages, and even those are stored for just 30 days before being deleted.
The complaint states that Facebook is well known for making use of user information as part of its business model:
WhatsApp built a user base based on its commitment not to collect user data for advertising revenue. 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 Whats App users into the user profiling business model.