US-based Dow Chemical, which had problems with pornographic e-mails earlier this year, said it will sack up to 40 employees this week because of new violations.

The two cases are unconnected, according to spokeswoman Kanina Blanchard.

She added that Dow doesn't monitor e-mail and said that these violations, which took place at the company's Freeport, Texas, location, came to light as a result of complaints by other employees.

"When employees make a specific complaint - as in this case - it triggered an investigation which included a review of the servers which host the email accounts," she said.

Employees who had pornographic or violent materials in their accounts were investigated, she said. Those who actively brought in, saved and disseminated the material, those who had material that was extremely graphic or violent in nature, and those with histories of violating Dow policies were singled out for termination.

"This was a minority of employees," she said, and employees who innocently received pornographic materials were not investigated.

"I personally have received off-colour or inappropriate emails," she confessed. "Once you get on the spam lists, you all know what you get. But this is not the kind of activity that you would get questioned about."