Some iOS 10 users have reported that using Airplane mode permanently disables mobile signal on their phone. Apple is now investigating the claims.

It's unclear whether the issue is affecting iOS 10 or the iPhone 7 and iPhone 7 Plus specifically, although it appears to be mostly affecting US customers who purchased an iPhone 7 through AT&T.

MacRumors notes that the iPhone 7 uses different modems depending on the network operator they're purchased through, with AT&T's iPhone 7 using an Intel modem rather than the Qualcomm unit used by rivals Sprint and Verizon.

Some users have found that restarting their device solves the problem, however others have been forced to return their device to Apple in exchange for a new one.

A video uploaded to YouTube shows an iPhone 7 with no cellular service, next to an iPhone 6S connected to a 4G signal. According to the owner of the video, the phone lost signal after turning on the device's Airplane Mode and then switching it off again.

They told MacRumors: "All of a sudden today my iPhone 7 Jet Black model started not getting internet service – can't make outbound calls or receive calls – even though it showed 4 bars. I then put it in Airplane Mode, and back off, then it showed no service. It got pretty warm in the top right-hand corner.

"I then took a video of my wife's iPhone 6S right next to my iPhone 7, put them both in Airplane Mode, and then switched Airplane Mode off and you can see immediately that the iPhone 6s gets signal instantly, and the iPhone 7 just sits there searching. I then took her SIM and put it in my iPhone 7, no luck, put my SIM in her phone, and it got signal right away."

IBTimes UK tested out the reported Airplane Mode bug and found to have no problems regaining cellular connectivity.

While Apple hasn't seen anything on the scale of exploding smartphones, the launch of its latest products hasn't been smooth sailing. In addition to finding hardcore porn in iOS 10's new GIF search feature, users have also reported handsets freezing and connectivity problems with Apple's Lightning EarPods.

Apple has told network providers that customers who report the latest problem should be instructed to restart their phone, and remove and then reinsert the SIM card if the issue persists.