South Korea's telecommunications regulators are looking into suspected violations of in-app payment rules.

In a statement, the Korea Communications Commissions said that it conducted an inspection of Apple, Google, and One Store since May 17 to determine if they have violated in-app payment laws. It could include blocking the registration, renewal or inspection of mobile content that uses third-party payment methods.

If the new probe discovers malpractice, the KCC may issue correction orders and impose fines up to as high as two percent of the average annual revenue from relevant business practices, but there is as yet little detail on the specific violations of the law.

A new South Korean law prohibits app store operators from requiring developers to use their own in-app purchase systems. The change allowed developers to offer alternative payment systems in South Korea.

It's not clear why Apple is under investigation, given that it now allows developers to offer third-party payment systems. It is possible that the KCC deems Apple to have taken too long to comply with the change in the law since it came into effect in March, but Apple only began telling developers that they could use third-party payment systems in June.