U.S. social media group Facebook seems ready to publish categories of data it collects from users, an Austrian student group lobbying for stricter privacy rules said on Tuesday.

Facebook had agreed in December to overhaul privacy protection for more than half a billion users outside North America after a three-month investigation found that its privacy policies were overly complex and lacked transparency.

This (data) access issue as well as having disclosed all the data categories they are holding about users is something where we found some progress, Max Schrems, spokesman for the europe-v-facebook.org group, told reporters after meeting Facebook representatives in Vienna on Tuesday.

The main issue is that they have limited resources, especially for the access requests. I have the feeling that they are kind of thinking if they can get by without making full access to the raw data.

The probe by the Irish Data Protection Commissioner (DPC) at the U.S. group's international headquarters in Dublin said users were at risk of unknowingly publicizing personal details.

Schrems said it was absurd that a group of individual citizens was trying to hold a multinational company like Facebook to account on privacy rules, but said the European Union would probably take a more active role in the future.

His group had filed 22 complaints against Facebook that centre on allegations that Facebook gathers personal data that users had not authorized or thought they had deleted.

(Reporting by Michael Shields; Editing by Helen Massy-Beresford)