TD Bank spokeswoman says about 1,000 Canadians with U.S. accounts could be affected after some data tapes containing personal information were misplaced, which also affects an additional 260,000 clients south of the border.
Maria Saros Leung says letters will be sent to those customers by next Friday.
But she says in an email that the bank is not classifying the incident as a breach since there's no evidence of criminal activity.
TD Bank has confirmed that unencrypted backup data tapes were misplaced during transport in March and said it has started notifying about 260,000 customers from Maine to Florida.
The U.S.-based subsidiary says in a statement it has no evidence the data on the tapes is being used for any inappropriate purpose and is calling it an "isolated incident."
It says an internal investigation has been launched and the incident reported to law enforcement.
The missing tapes contained personal information including account information and Social Security numbers, TD spokeswoman Rebecca Acevedo told The Associated Press on Friday.
She said the company was not aware of any misuse of customer information but it has not ruled out the possibility and is monitoring the situation.
"TD takes customer privacy very seriously and we have policies and procedures in place to ensure appropriate handling of private customer information. We understand this is a difficult situation for our customers and apologize for the inconvenience," the bank's statement said.
It said those customers affected will be offered credit monitoring and identity theft protection.
TD Bank, which has about eight million customers, is based in Cherry Hill, N.J., and Portland, Maine.