British employers may not be allowed to monitor their employees' private email or internet use at work in the future, or use hidden cameras, without staff knowledge unless a criminal investigation is under way.

According to a draft Code of Practice on data protection from the Information Commission, a copy of which has been seen by PC Advisor, employers should not open email when there is reason to believe they are private, even if they are sent or received using a work computer during work hours.

Employers should monitor the time spent on the internet as opposed to the sites visited or contents viewed.

The full Code of Practice is due for release within six to eight weeks, an Information Commission spokesman said.

This Code is the Commission's interpretation of the Data Protection Act 1998, he said, and so will act as guidelines for employers unsure about the rules, the spokesman said.

Employers who deviate from the Code could find themselves no longer in compliance with the Data Protection Act. However, "different industries differ so much that there can't be hard and fast rules — these are just a general interpretation", he said.