The numbers involved suggests that this is one of the biggest cases of its kind so far.

Two employees in the company's Scotland office were dismissed while staff have been suspended elsewhere in the UK and in Ireland.

"HP can confirm that this involves the viewing and sharing of unauthorised and inappropriate material," a statement from HP said.

Not criminal

More and more firms have been cracking down on employees' use of e-mail to send pornography and tasteless jokes.

So far, Hewlett Packard considers the matter a violation of company rules, but not a criminal matter.

The 150 staff on suspension are made up of 60 permanent staff and 90 contract staff and their fate will be determined following a company investigation.

The issue of e-mail abuse has become one of increasing concern for employers.

Across the world

The latest generation of e-mail scanners allows employers to sift workers' correspondence for words deemed unsuitable.

The most high profile case of "e-mail abuse" involved a lawyer at London law firm Norton Rose.

Bradley Chait forwarded copies of a smutty e-mail sent to him by his girlfriend.

Within hours it had spread from Norton Rose to other London law firms before making its way across the world as far as New Zealand.