The Data Protection Commissioner has reported a doubling of the number of cases investigated last year.
At the launch of the commission’s annual report, Billy Hawkes said finding a balance between security, crime prevention and commercial interests, and the interests of the private individual was increasingly on his agenda.
Established in 1988 to protect the individual's right to privacy, the commission conducted 658 separate investigations last year, compared with 300 in 2005.
The commission says the gradual erosion of people’s private space needs to be addressed by giving people control over how information they might disclose is used.
Direct marketing complaints about telecom providers, the gathering of excessive private data by public and private bodies, and the failure of several nightclubs to provide access to CCTV footage were among the matters investigated by the commission.
Mr Hawkes said he would continue to crack down on the problem of unsolicited text messages being sent to mobile telephones.