Pocket Gamer said that the charts for the US iOS App Store currently feature several apps of Chinese origin, which only include content in the Chinese language, and which are accompanied by user reviews containing claims of fraud.

According to the report, the freemium apps have billed customers for in-app purchases, even when users state that they have not played the games or downloaded the titles involved.  

Pocket Gamer said a similar pattern had been noted in the UK late last year.

So far, it is unclear how the apps have climbed the charts and made unauthorised purchases, although it was suggested that malware installed on jailbroken devices or stolen log-in details were both options.

One of the developers named in the report, Shanghai MUHE, told Pocket Gamer that it had been reporting possible frauds to Apple since October 2011, to no avail. Several other companies were also implicated.