It raises the claim against the social networking site to $7.7 million (Rs.4.6 crore), media reports said.
Max Schrems wants to receive damages of 500 euros (Rs.41,000) per user for the violations by the social network, urging the 1.32 billion Facebook users to join him in his legal battle.
“It is much more than we expected,” Schrems, who formed Europe-v-Facebook campaign group, was quoted as saying.
Schrems started inviting Facebook users outside the US and Canada Aug 1 to join his lawsuit against the company.
The lawsuit is lodged with the commercial court in Vienna, Austria.
About 50 percent of those signing up are from Austria and Germany, Schrems said, adding that the vast majority of backers come from the EU.
The legal proceeding will run as a class action because the Austrian law allows a group of people to transfer their financial claims to a single person.