Like any powerful new technology, the Internet can be used as a force for good or for harm.

Its positive applications are endless. Our own website, www.thisisyork.co.uk, demonstrates how the Internet is an unrivalled communications tool. Former North Yorkshire residents now living as far away as the United States and Australia keep up to date with events in their old backyard by reading the Evening Press on-line.

The Internet's ability to shrink continents was illustrated earlier this year when it enabled two York sisters to contact family they never knew they had.

They were united with their four half-brothers and sisters in Australia after a genealogist discovered the family connection while researching on the web.

And the network allows human rights campaigners in oppressive regimes to send and receive information in a way that no other media can.

But this same power can be abused. There is a lot that is unsavoury on the Internet, including hard-core pornography and material inciting race hatred. Bomb-making instructions can be found, if you know where to look.

And now, in a direct challenge to British authority, a sacked agent has published a list of MI6 spies on a web page.

Let us be straight, the actions of Richard Tomlinson are not just incredibly irresponsible, they are treasonous. By publishing the identities of serving agents, he is putting their lives, and British security, at very real risk.

Tomlinson's previous attempt at sabotage landed him in prison. He was jailed in 1997 for breaking the Official Secrets Act when he showed the transcript of his book about MI6 to an Australian publisher.

British law was able to deal with a threat that came in the traditional form of a book.

But the law is not so effective in amorphous, intangible cyberspace.

Hard line advocates of the Internet want it to remain entirely unregulated. They are right to consider the web a champion of freedom of expression, and it is important to keep any form of censorship to a minimum.

Nevertheless, the net must be policed. Otherwise it will become a refuge for serious criminals.

A legal fight is now under way in the United States to try and put a stop to Tomlinson's website. He has already moved the pages from a Swiss site to an American one after Britain obtained an injunction in Geneva.

As this example proves, international co-operation is vital if the web is to be policed effectively. New globally-agreed laws are needed to curb the web's most dangerous excesses. It is time the Internet's power was accompanied by some responsibility.

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.