The matter is under investigation by the Data Protection Commissioner.
Electric Ireland says Gardaí and the Data Protection Commissioner, Athlone's Helen Dixon, are investigating the compromising of around 8,000 customer accounts.
It says it's aware an employee working on its behalf may have inappropriately accessed some customer accounts, leading to the potential misuse of personal and financial information.
All customers who may have been impacted have been written to, and only those who have received a letter need to take action.
Electric Ireland says it fully appreciates the gravity of this issue and the concern and inconvenience it will create for those affected.
Calls Grow For 24 Hour Garda Station In Edenderry After Arson Attack
Appeal Date Set For Jozef Puska Over Murder Of Ashling Murphy
Offaly Town Demands Meeting With Garda Commissioner And Justice Minister
Ireland’s First Kidney Pancreas Transplant Recipient Dies Aged 68
Quality Of Life To Drive Offaly’s Appeal For Foreign Investment - Anna Marie Delaney
Hundreds Of Mourners Gather For Tadgh Farrell's Funeral
Dancing With The Stars ‘A Once In A Lifetime Opportunity’ - Rose Of Tralee
Uisce Éireann To Submit €6b Water Project Plan
Pedestrian Killed In Midlands Crash
Gardai Arrest Four Men Over Laois Prison Assault
Maura Higgins Set For Traitors US
Man Taken To Hospital Following Alleged Westmeath Assault
Osteoarthritis Programme Launched At Midlands Hospital
Laois County Fire And Rescue Service Welcomes Two New Fire Appliances
Offaly TD Welcomes New IDA Ireland Investment
Gardai Conduct House Searches In Connection With Offaly Arson Attack
Funeral For Offaly Arson Attack Victim To Be Held Today
Emergency Services At Scene Of Offaly Crash
Tadgh Farrell’s Father Denied Compassionate Bail To Attend Son’s Funeral