O2 and IT partner IBM have revealed a back-up tape potentially containing customers' personal data has been lost, more than a year after it went missing in Ireland.
The telecoms provider says IBM only informed it the tape, used for routine IT back-up work, had been misplaced during the summer, some months after the incident occurred.
Ireland's Office of the Data Protection Commissioner, which is investigating the incident, ordered O2 to inform its customers about the tape loss.
The data on the missing tape is unencrypted, but O2 says it's stored in a format that makes it inaccessible to any outsider without specialist technology. The firm suggests that while the information is currently unaccounted for, "it is possible that the tape has simply been misplaced within an otherwise secure location in O2".
In a statement, O2 said that it's unlikely that customers' personal data has been compromised, but that it can't be certain.
"While we can't be definitive, we believe there is a low risk to customer data privacy. The tape in question was one of a number produced on a daily basis containing a snapshot of certain data held on some of the company's systems at a particular moment in time. Some back-up tapes don't contain any customer data at all."
The company apologised to customers, adding that such an incident hasn't happened before and the tape loss is being examined to prevent further such incidents in future.
"O2 sincerely apologises to its customers that the incident in question occurred. We also want to reassure customers that stringent measures have since been taken to ensure such an incident does not happen again."