Facebook ... had 22 separate complaints filed against it by europe-v-facebook.
An Austrian student group plans to go to court in a bid to make Facebook do more to protect the privacy of its 1 billion users.
Campaign group europe-v-facebook, which has been lobbying for reforms at the US company for more than a year, said it would appeal against decisions by the data protection regulator in Ireland, where Facebook has its international headquarters.
The group has filed 22 separate complaints against Facebook, winning some concessions including pushing the social network to switch off its facial recognition feature in Europe.
But it said on Tuesday the changes did not go far enough and it was disappointed with the results of an audit carried out by the Irish Data Protection Commissioner (DPC) in response to its complaints, which it now plans to challenge in court.
"We'll be fighting Facebook via the DPC," said Max Schrems, the group's founder.
The move is one of a number of campaigns against the giants of the internet, who are under pressure from investors to generate more revenue from their huge user bases but also face criticism for storing and sharing personal information.
Internet search engine Google, for example, has been told by the European Union to make changes to a new policy that pools data collected on users of its services including YouTube, gmail and Google+, from which users cannot opt out.
Facebook's shares have dropped 40 per cent in value since the company's record-breaking $US104 billion initial public offering in May as revenue growth has slowed.
"The latest Data Protection report demonstrates not only how Facebook adheres to European data protection law but also how we go beyond it, in achieving best practice," a Facebook spokesman said in an emailed comment.
"Nonetheless we have some vocal critics who will never be happy whatever we do and whatever the DPC concludes."
Last month, Facebook proposed to combine its user data with that of its recently acquired photo-sharing service Instagram, loosen restrictions on emails between its members and share data with other businesses and affiliates that it owns.
Late on Monday, it invited users to vote on the proposed changes to its policies, which have generated almost 90,000 user comments as well as concerns from some privacy-advocacy groups and a request for more information from the DPC.
Ian Maude, an analyst at London-based technology and media analysis firm Enders Analysis, said privacy concerns were not stopping more and more people from using social networks.
Among its complaints, europe-v-facebook said more than 40,000 Facebook users who had requested a copy of the data Facebook was holding on them had not received anything several months after making a request.
Ireland has become a hub for the international operations of US technology firms including Google and Microsoft, who are attracted by a generous tax regime and in return create employment for thousands.
Gary Davies, Ireland's deputy data protection commissioner, denied Facebook's investment in Ireland had influenced regulation of the company.
"We have handled this in a highly professional and focused way and we have brought about huge changes in the way Facebook handles personal data," he said.
Europe-v-facebook said it believed its Irish battle had the potential to become a test case for data protection law and had a good chance of ending up in the European Court of Justice.
Schrems said the case could cost the group around €100,000 ($A125,000), which it hoped to raise via crowd-funding on the internet.