SASKATOON -- Saskatchewan Blue Cross says it's been the victim of a cyber breach.

In a statement on its website, the not-for-profit insurer said its security team witnessed "unusual network activity" on April 20.

"(We) immediately initiated our incident response plan, which included proactively shutting down certain key systems and services," the statement said.

"At this stage, we can confirm that the system outage was caused by a cybersecurity incident."

Blue Cross said it is working with cyber security experts in its investigation and its continued work to restore services.

However, the insurer said this point it is unable to determine with "certainty" how the breach might affect Blue Cross members.

"We are working to get all the facts and will provide updates as soon as we have more to share. We apologize for the uncertainty right now."