Apple has said it is taking steps to remove a malicious program found in a number of applications used by owners of iPhones and iPads in China.
It is thought to be the first large-scale attack on Apple’s App Store.
The American firm said hackers had embedded a malicious code into the apps by persuading developers to use a counterfeit version of the firm’s own software.
The program called XcodeGhost allows hackers to collect data from devices.
The infected applications include many used by iPhone and iPad owners in China such as Tencent’s hugely popular WeChat app, a music downloading app and an Uber-like car hailing app.