Insurer Aflac said on Friday it identified suspicious activity on its network in the United States on June 12.
The company said it has reached out to third-party cybersecurity experts to investigate the incident and has commenced a review of potentially impacted files.
These files contain personal information of its customers, including social security numbers and health-related details, it added.
Shares of Aflac fell 1.6 per cent in premarket trading.
