More than a billion older Android smartphones with legacy operating software are a security risk and could be exposed to data theft and malware attacks according to new research by Which?

Around four in ten of Android users around the world are still on version 6.0 or below of Google’s mobile software even though there wasn’t a single security patch for version 7.0 or lower last year.

Which? tested five smartphones including the Samsung Galaxy S6 and Motorola X to see whether these older devices could be targeted with malware.

The conclusion was a resounding yes, as every model was infected.

The consumer watchdog said Google did not provide assurances that it would do more to support “end of life” devices that no longer receive official updates after sharing its findings.

Which? Computing editor, Kate Bevan said Android devices, even premium, expensive smartphones, often have a short shelf life due to the loss of support.

It means millions of users with phones that are only a few years old are now at risk of being a victim of hacking or fraudsters.

He added: “This could result in personal data being stolen, getting spammed by ads or even signed up to a premium rate phone service.”

Which? urged the UK government to move forward with legislation that would force mobile phone manufacturers to be more upfront about security updates and the time frame for support.

Android users who are worried should check in the Settings menu to see whether they can update to new software.