File photo of an iPhone 5S. Source: Edward Smith/EMPICS Entertainment

A BUG IN Apple’s FaceTime app allows users to listen to audio from the phone of the person they are calling before the person has accepted or rejected the call.

The bug was first reported by tech website 9to5Mac.

It is triggered when, while making a FaceTime call, a user swipes up from the bottom of the screen and taps Add Person and adds their own phone number.

This allows them to start a group FaceTime call including themselves and the audio of the person they originally called, even if the second person hasn’t answered the call.

Tests carried out by the Guardian show that, in some circumstances, the bug also allows users to see video of the person they are calling before they pick up

If the recipient of the call presses the power button on the side of the iPhone, an action typically used to silence or ignore an incoming call, their phone will begin broadcasting video to the person calling them -  raising obvious concerns about privacy issues.

In a statement, an Apple spokesperson said the company is “aware of this issue and we have identified a fix that will be released in a software update later this week”.

Apple has taken Group FaceTime offline in an attempt to address the issue in the meantime.

The bug works on iPhones and iPads running iOS 12.1, and Apple PCs running macOS Mojave, CNN reports. To avoid being affected by the bug, people can disable the FaceTime app until the issue has been resolved.