If you are worried by sex on the internet (see Richard Reeves, page 30, and Johann Hari in NS, 7 March), maybe you should be even more worried by the violent imagery available. Just by typing words such as "murder" and "blood" into Google, today's teenagers can access footage ranging from animated Tarantino-style bunny massacres to actual al-Qaeda beheadings.
One website, called www.ogrish.com , has attained cult status among teenagers. Totally legal under US law, it makes users confirm that they are at least 18 before they go beyond the home page. But though younger users are threatened with perjury, it takes no more than the click of a mouse to get through to "beheading videos, execution images, accident pictures, gruesome scenes from Iraq etc".
Ogrish is probably the most hard-core of a range of bloodthirsty websites that have become popular with schoolchildren and students. A survey by Sonia Livingstone, professor of social psychology at the London School of Economics, found that 31 per cent of children aged from nine to 19 have accessed such gory websites. "There has always been a point in adolescence when teenagers search out this kind of material," she says, "But on the internet there's no context to the way they experience it. Horror movies, for example, are made with some eye to their audience - and there's some kind of resolution to what happens. On the web, there isn't that kind of control - it just brings increased availability, variety, and convenience."
Dan Klinker, the Dutchman who set up www.ogrish.com , argues that people have the right to see what's really going on in the world. "We feel that only by showing the uncensored footage can we get the full picture and realise that the threat of terrorism and evil in this world is real. We don't force anyone to visit; we simply provide people with the opportunity."
The playwright Philip Ridley was widely criticised last month for his drama Mercury Fur, which depicts three adolescent boys preparing a child for sacrifice, after they have been paid by a businessman wanting to appear in his own snuff movie. Accused of indulging in "sick fantasies", he claims that he is merely chronicling a new sensibility, which is partly informed by the "cult" status of sites like www.ogrish.com .
"What worries me," he says, "is the way these sites link sex with violence, so that teenagers are confusing them emotionally in their search for the next big thrill."
According to Sonia Livingstone, research shows that the combination of violence and porn is more disturbing to teens than either in isolation. On most of the sites, the link is unavoidable, whether it's in the pictures of sexy girls at the side of the blackly humorous but worrying www.newgrounds.com , or the declaration on www.gorezone.com  (officially for those over 21) that you "will be exposed to . . . scenes of death, violence, dismemberment, sexually explicit material, nudity, and sexual activity".