By publicly indicating on LinkedIn that you are looking for a different job, you could be in breach of an employee's ''duty of fidelity''. ''I think the fact of doing that would be a breach of their employment obligations,'' she said.

In Britain an employee was sacked after he made negative comments about his employer on LinkedIn and also said he was free to be contacted for ''career opportunities''. A decision is yet to be handed down in that case.

Ms Jenkins said LinkedIn contacts were another fraught area, particularly in industries where contact lists are commercially sensitive, such as professional services or recruiting. ''The other thing, which is quite untested, almost everyone is collecting a network of contacts, which in the past would have been a confidential client list.''

Staff, when they leave, can face restraints when they go to a competitor that they should not contact clients. But on LinkedIn, a simple update by an employee that they have moved jobs could tell hundreds of contacts of their new role.

Ms Jenkins said employers could be able to restrain employees from making an update for a certain period of time or negotiate with them to delete contacts they acquired while working for them.