The Data Protection Commissioner has said he will carry out audits of all the major social networking companies that have operations in Ireland.

Billy Hawkes said Ireland had a significant responsibility to the rest of Europe, as many of these companies had located their European headquarters in the country and fell under its jurisdiction.

He said LinkedIn and Twitter would be among those audited.

Mr Hawkes said staff numbers had been increased in his office and it had been allocated a bigger budget so that it could handle such audits.

He was defending his office's audit of Facebook, which was carried out last year.

A European privacy campaign group is currently planning to take the commissioner to court, claiming the audit did not go far enough.

The audit found that Facebook was broadly compliant with Irish and European law.

Max Schrems, the Austrian law student behind the Europe v Facebook group, said Facebook was retaining deleted data on people, both users and non-users.

He said this raised serious concerns about personal privacy.

Mr Schrems is seeking final decisions on 22 complaints against Facebook filed with the commissioner.