The Consumer Affairs Agency said Wednesday it has asked the operator of Apple Inc.'s iTunes Store in Japan to investigate false billing claims the agency has received involving consumers who say they were billed for music and software they never bought.

In an open letter posted on its Web site, the agency asked iTunes K.K. to respond to such questions as how many cases of false billing claims the store is aware of and to provide details on the complaints and on the amounts stated in the bills.

It also asked the company to list what steps are being taken over the cases and how it plans to identify the cause of the complaints if it has not yet done so.