Austria’s Data Protection Authority opened an investigation into operator A1 Telekom Austria amid accusations the company flouted rules on storage of customer information, Kurier reported.

The probe centres on the operator’s storage of data from tens of thousands of users, some dating back five years. A complaint made by a Vienna-based lawyer alleges information was stored for an indefinite period of time without the permission of the subscribers concerned.

Austrian law states customer and charging data should be deleted after a set term, which varies depending on the type of information held.

Data reportedly retained comprised both billing and usage information, including phone numbers contacted and internet access details. The infringement is said to involve consumer and enterprise customers of its mobile, fixed line, Bob and Red Bull Mobile units.

A1 was given two weeks to respond to the regulator before further action is taken.

In a statement to Kurier the operator apologised for “non-timely” deletion of the data. It added only a small number of employees had access to the information, which had now been transferred to an internal investigation team and deleted from its main database.