The prestige Radisson Blu hotel chain has become the first in the world to roll out a new technology that can spot guests receiving or distributing real images of child porn.

The company plans to install the child abuse-free zone system from Swedish startup NetClean Technologies in the Scandinavian wing of the company immediately before extending it in time to cover the entire 235 global chain of hotels and resorts.

Unlike anti-porn systems based on website and keyword filtering, NetClean's technology is based on comparing the files it detects against a 400,000 image database of real images largely compiled by the Swedish police during paedophile investigations.

The system can be installed on a network gateway or PC, although in the case of the Radisson Blu deployment, the gateway option is the only practical one, which means monitoring files moving into and out of each hotel's network.

"Many collectors of child abuse images carry the images with them when they go away on business or on holiday," said NetClean CEO, Christian Sjöberg. "Organisations need to protect against this. No business wants to be portrayed as careless or indifferent about their networks being used to allow child abuse images to be viewed or passed around," he said.

What the chain hasn't said, however, is how it will deal with guests detected to be receiving or sending child porn images by the system. Because NetClean's technology detects known images based on digital fingerprinting, assuming there has not been a false positive, it is effectively detecting a criminal offence in many countries. In the UK, that would mean telling the police.

Guests will be made aware of the system through an information tag beside the data port in hotel rooms, or when signing up for Wi-Fi. Ideally, this warning would also explain the seriousness of child porn trafficking.

Hotels have a tricky job here. Part of the business model of some chains involves selling adult movies to guests at premium rates. This won't include child porn, but does give them the job of communicating the distinction between legal smut and illegalabuse in a clear manner.

Part of the upmarket Rezidor Hotel Group, Radisson Blu's UK locations include London and Brighton.