A smartphone user shows the Facebook application on his phone in Zenica, in this file photo illustration
Facebook admits its iOS app is killing iPhone battery life as it continues to retrieve data even if you've told it not to. REUTERS

If you're wondering why your iPhone battery life is rapidly draining away since you upgraded to iOS 9, then you might want to look at your Facebook app. The social media giant has held up its hands to admit that its iOS app is causing battery issues.

This will add to the iPhone 6s battery draining woes, as the the Facebook app has always been known as a bit of a battery killer. According to information gathered by blogger Matt Galligan, since the iOS 9 update the app sucks life from batteries due to excessive background usage and not going to 'sleep' when you exit it.

Galligan found the app was responsible for 15% (3.4 hours) of his total battery drain over a seven-day period – more than any other app on his phone. Shockingly, this was with background app refresh disabled - a feature that purports to preserve battery life.

Facebook app will kill your iPhone battery

According to reports gathered by blogger Nick Heer, turning off background app refresh is actually worse for the battery as Facebook is "creating channels to continue refreshing their app in the background when the user has explicitly stated they do not want it to."

A Facebook spokesperson responded to TechCrunch regarding the issue by saying: "We have heard reports of some people experiencing battery issues with our iOS app. We're looking into this and hope to have a fix in place soon."

As to what is 'really' causing the issue of battery drain, some user conspiracy theories speculate the app is hijacking the iPhone's audio so it can nefariously continue to play videos in the background silently without you knowing.

How to make your iPhone battery last longer

If you're using the Facebook app and have found your battery to drain suspiciously quickly then the best way to fix it would be to delete the app and login via your mobile browser such as Safari or Chrome. Facebook has said it is working on a fix for the issue so you could reinstall it then.