IT security professionals are pressing the Home Office to give IT staff legal protection if they have to handle obscene material downloaded by employees or hackers on company networks.
Staff are concerned that they have no legal defence to charges that carry a five-year prison sentence if they copy or view files containing child pornography during a legitimate investigation into internet misuse.
Internet service providers are pressing the government to use the forthcoming Sexual Offences Bill to give IT staff legal protection from prosecution if they encounter obscene material during their work.
The Bill will give legal defences to police and forensic investigators, providing they have written authorisation to copy pornography from a chief police officer, but security professionals say this will be little help to IT staff who stumble across illegal images.
"The Home Office has not done its homework. The problem for employers is that their ITstaff are likely to come across this material by accident," said Peter Sommer, security expert at the London School of Economics.
The London Internet Exchange, which represents the majority of the UK's ISPs, said the law places employers and their staff in an impossible situation.
"If a systems administrator copies this material and sends it to the police, that is a breach of the law. So far there have been no prosecutions but given that the law is being reformed, it is time to give IT staff a stronger footing," said London Internet Exchange regulation officer Malcolm Hutty.
ISPs are concerned that they could be held liable in employment tribunals or face damaging headlines in the press if they ask staff to investigate complaints about child pornography.
Richard Starnes, an internet security professional, said it was common for IT staff to encounter obscene images, particularly when investigating cases of internet abuse by employees. In some cases, hackers have used company or university computer systems to hide caches of illegal photographs.
The Home Office said that, in practice, although there is only limited protection in law, the Crown Prosecution Service would be unlikely to prosecute IT staff who have acted in good faith.
"We are aware of the concerns that have been raised by the ISPs and we are currently in discussions with the police and industry to try to address them. It is important that we get this right," a Home Office spokesman said.