Many iPhone 4S users have been reporting reduced battery use on their smartphones with forums abound with unhappy users.

Apple are apparently now investigating the issue by contacting people who've had problems in order to find a solution. They'll be keen to avoid any widespread issues , such as the antenna problem which plagued the iPhone 4 launch.

The common consensus is that the problem lies with iOS 5's "Setting Time Zone" feature which automatically updates your clock based on your location. Apparently, the feature is constantly running which drains battery because it uses WiFi and aGPS to work out your location.

For the time being 3G would recommend disabling the feature which can be found at System Services - Location Services. However, be warned that when changing time-zones your clock won't be automatically updated.

If this is the problem causing the reduced battery issues then Apple will relatively pleased because it should prove relatively easy to fix.

You can buy your Apple iPhone 4S on Three by clicking here.