According to the Austria-based Europe vs Facebook group, nearly 60,000 people have signed up to the suit, 25,000 of which have assigned their claims to join the class action.
At 500 euros claim per user for the reported violations by the social network, Facebook could potentially have to pay out $16,577,438, media reports said.
The 25,000 registered now are users largely in Europe with German-speaking countries representing the majority of responses, Techcrunch reported.
The other countries strongly represented include the Netherlands, Finland and Britain.
An Austrian law student Max Schrems filed the class action lawsuit in Vienna against Facebook over privacy violations.
Ireland is the headquarters for Facebook's international operations.