The Northwest Territories Power Corporation has sent a letter to its customers telling them about a data security breach involving their personal information earlier this month.

The company says that on Jan. 13, the company replied by email to a customer inquiry and attached the wrong file to that outgoing email.

The file contained a list of customer names, meter addresses and account balances. NTPC says the file did not include any banking information, credit card numbers or telephone numbers.

The company says the error was discovered immediately and the email recipient was contacted. It says the recipient confirmed that neither the email nor the attachment was opened, and both were deleted. In addition, the email recipient has signed a confidentiality agreement.

In a statement, Emanuel DaRosa, president of the Power Corporation, said NTPC was not required to disclose the data breach but felt a "moral obligation" to do so.

"NTPC takes the security of its customers' information seriously and sincerely apologizes and regrets that this situation has occurred," he said in the statement.

"We want to assure our customers that we have policies and procedures in place to protect their privacy and NTPC has taken further precautions to ensure that this does not occur again."

Affected customers should receive letters from NTPC within the next 14 days.

Customers with questions can call NTPC's Customer Service line at 1-855-575-6872.