Facebook is also facing questions over reports that it collected years of data on contact names, telephone numbers, call lengths and information about text messages from Android users. Cook County's State Attorney Kimberly M. Fox says both companies violated Illinois' fraud law.
Now it's rolling that initiative out to Facebook users in all countries and languages. Denham said the prime allegation against Cambridge Analytica is that it acquired personal data in an unauthorized way.
Meanwhile, the chief law enforcement officers for 37 U.S. states and territories are demanding to know when Facebook learned of the breach.More news: US, EU expel Russian diplomats in response to nerve attack in UK
Opinion polls published on Sunday in the United States and Germany cast doubt over the level of trust people have in Facebook over privacy, as the firm ran advertisements in British and US newspapers apologizing to users.
How did Facebook monitor what these [third-party] developers did with all the data that they collected? "Many people told me they thought that if we could turn down the temperature on the more divisive issues and instead focus on concrete local issues, then we'd all make more progress together".
On Sunday, Senator Mark Warner - the top Democrat on the Senate Intelligence Committee - said Zuckerberg "needs" to testify before Congress.
The officers say in a letter to Facebook chief executive Mark Zuckerberg that users" trust in the social media platform is "broken'. When users ask to permanently delete their accounts, the company suggests: "You may want to download a copy of your info from Facebook". Germany's justice minister said Facebook's promises were not enough.More news: Waymo to create luxury, self-driving electric auto with Jaguar
Many tech companies say they collect data to learn more about their customers - their habits and preferences - and deliver better service.
The social media giant said the company remains "strongly committed" to protecting people's information and that it welcomes the opportunity to answer the FTC's questions. According to CNN, the FTC has launched a "non-public investigation" in an effort to learn more about their current privacy practices.
A statement from Tom Pahl, acting director of the Federal Trade Commission's Bureau of Consumer Protection, said: "the FTC takes very seriously recent press reports raising substantial concerns about the privacy practices of Facebook". The fact is, European regulators are already forcing him to do so.
Warner repeated calls for Zuckerberg to testify in person before US lawmakers, saying Facebook and other internet companies had been reluctant to confront "the dark underbelly of social media" and how it can be manipulated.More news: YouTube TV Will Sponsor The NBA Finals
Zuckerberg said in the ads, "This was a breach of trust, and I'm sorry we didn't do more at the time" when Kogan passed on the Facebook data to Cambridge Analytica."We're now taking steps to make sure this doesn't happen again".