The Japanese units of two major insurance companies say the personal data of a combined 2 million customers has been illegally accessed. They cited possible hacking at third-party business partners.

Aflac Life Insurance Japan says the breach affects more than 1.3 million holders of the firm's cancer insurance policies.

Aflac says the stolen data include names, ages, genders, and policy numbers.

Zurich Insurance says details of more than 750,000 present and past policyholders of its auto insurance may have been leaked.

The company says the hacked information likely includes names, genders and birthdates, as well as email addresses and policy numbers.

The insurers say they have not confirmed any unauthorized use of personal data so far. They say the US firms they outsource some operations to may have been hacked.

The companies have apologized and say they will contact affected customers individually.