05/12/2016 16:00 GMT | Updated 05/12/2016 16:04 GMT

Apple Has Revealed Why Some iPhone 6s Devices Shut Down Unexpectedly

But the explanation has only been posted to its Chinese site.

Apple has finally explained why some iPhone 6s devices are unexpectedly shutting down, but only on its Chinese website. 

Last month, the firm announced a free battery replacement programme for customers whose handsets were randomly shutting down.

But until now, it hadn’t explained the cause of the defect. 

While there’s no mention of the explanation on other sites, there’s an English language version, as MailOnline first noted, on the Chinese site.

Robert Galbraith / Reuters

The post states: “We found that a small number of iPhone 6s devices made in September and October 2015 contained a battery component that was exposed to controlled ambient air longer than it should have been before being assembled into battery packs. 

“As a result, these batteries degrade faster than a normal battery and cause unexpected shutdowns to occur. It’s important to note, this is not a safety issue.”

The firm added that the phone is designed to shut down automatically “under certain conditions, such as extremely cold temperatures”. 

“To an iPhone user, some of those shutdowns might seem unexpected, but they are designed to protect the device’s electronics from low voltage.”

Last week, the China Consumers Association asked Apple to extend the replacement programme to models beyond the iPhone 6s.

It claimed the problem also affected iPhone 6, iPhone 6 Plus and iPhone 6s Plus devices produced during the sam time. 

But Apple reiterated that that the issue only affects iPhone 6s models. Users can check if their iPhone is eligible for a new free battery online

Apple did not immediately respond to HuffPost’s request for comment.