Over half of all UK employees store work-related files such as emails and documents in locations other than a shared computer network, posing serious security threats.

A survey by enterprise content management firm Tower Software found that 55 per cent of employees were guilty of these transgressions.

Some 49 per cent of PC users store work-related files in multiple locations, and 21 per cent use a memory stick.

Around 14 per cent of employees questioned admit to storing corporate material on the hard drive of their laptop, and nine per cent even store work-related material on personal devices.

Nearly eight per cent use portable hard drives for work file storage, and seven per cent use mobile devices such as PDAs and smartphones for emails, files and documents.

Paul Brenchley, EMEA vice president at Tower Software, said: "Worryingly, one per cent are unsure which of these locations they have stored work-related files.

"Employees at middle manager level seem to be worse at storing computer files in such places (62 per cent), compared to administration staff (43 per cent).

"Despite the meteoric rise in mobile working and popularity of mobile devices, I am surprised that these figures are so high."

Brenchley believes that warnings about corporate security, compliance and information control are simply not registering with many employees.

The use of memory sticks, for example, leaves many organisations in breach of security contracts that forbid the devices in corporate buildings or any other location with a corporate IP address.