Smartphone users are being warned after new research has discovered an alarming new security flaw that is being used to monitor online activity.

According to the research, the battery level of your smartphone is being used to monitor which websites you visit.

The study carried out by Princeton University explains how the smartphone battery status is being used to track your every move online.

The research looks at the smartphone battery status API, which is present in all the leading web browsers including Chrome, Opera and Firefox.

The API or (application programming interface) was introduced with HTML5 and is designed to inform websites on different battery levels and performance in order to serve up lower power versions of the site when required.

When it was first introduced back in 2015, concerns were raised that the battery life of users could be used to track them online.

By looking at a combination of battery life as a percentage and the amount of battery loss in seconds and then cross referencing this data with other online identifiers, sites could potentially pinpoint specific devices.

Say for example a user opened their local animal charity website on Firefox and then opened an animal hunting website using Google Chrome through a totally separate connection using a VPN, the two connections should be almost impossible to link with one another.

However, according to the research something like an advert that loaded on both websites would be able to tell that the two connections were linked from the same devil

The research from Princeton University found that tracking scripts used in the battery status API actually “fingerprints” a device allowing it to be continuously identified across a variety of different sites.

The research was highlighted earlier this week by Lukasz Olejnik who posted about it on his blog. Lukasz was one of the researchers who raised concerns about the smartphone battery status API in 2015.

“Some companies may be analysing the possibility of monetising the access to battery levels,” said Lukasz .

“When battery is running low, people might be prone to some – otherwise different – decisions. In such circumstances, users will agree to pay more for a service.”