CIBC is experiencing what the bank calls a "system issue" that's stopping many customers from logging in online, on the mobile app or by phone.

Customers reported problems logging in across all of the bank's systems early Friday morning, and the bank acknowledged an unnamed technological issue was at the root of the problem.

But in a statement to CBC News, the bank did not provide any details as to what the issue was, or when it would be fixed.

"We are currently experiencing a system issue affecting some of the ways our clients bank with us and are working to quickly restore full service," spokesman Tom Wallis said.

CIBC subsidiary Simplii Financial was also affected by the outage.

The bank was busily responding to individual customer complaints on its Twitter account on Friday.

"We have advised our clients through social media and other channels, and apologize for any inconvenience," Wallis said.