An Australian regulator sued Facebook on Wednesday (December 16), accusing it of collecting user data without permission.
It follows a slew of government efforts around the world to rein in the social network giant.
The Australian Competition and Consumer Commission (ACCC) said it was seeking an unspecified fine from Facebook for promoting a virtual private network as a way for people to protect their data while secretly using the information to pick targets for commercial acquisitions.
"The app was promoted as one that would protect your data, keep it secret, keep it safe," said Rod Sims, chair of the ACCC. "The reality was that Facebook was using data to monitor people's internet and app activity, for example, which apps you visited, how long you were on those app sites for and so it was using that data to work out various things that benefited it commercially."
The VPN product called Onavo was shut down by Facebook last year.
A Facebook spokeswoman told Reuters that the company was "always clear about the information we collect and how it is used," but added that Facebook will review the filing.
One legal expert told Reuters the Australian lawsuit may force the company to change the way it discloses its activities to users.
Earlier this year Australia also went ahead with plans to make Facebook and internet giant Google pay domestic media outlets for content that appeared on their websites.