Internet filters are little more than a sham, letting through porn, drugs, and bomb-making sites. Or so says Which?, the British consumer watchdog, which tested seven software filters on a random sample of 23 potentially offensive sites and 17 innocent sites. All seven – AOL Parental Controls v5, Cyber Patrol 4, Cyber Sentinel 1.6, Cybersitter 1999, net Nanny 3.1, PureSight 2.1 and We-Block 1.03 – allowed access to at least six sites with undesirable content. But whereas some filters let all manner of unsuitable material and net nasties slip through – only three barred a Nazi propaganda site - others blocked out harmless sites such as one showing poems by Wilfred Owen. Which? researchers also found it impossible to access the Lancashire County Council site through the Cybersitter product as it contained the words "sex" and "live" - even though the site was talking about "sex lives" rather than "live sex". Another concern raised by Which? was that some filters seemed to block out sites which slagged off the filter's company or software. "Although these filter systems provide some protection from offensive material, parents should not rely on them to block the information thoroughly," warned Graeme Jacobs, Which? editor. "They are not an alternative to parental guidance and supervision." Which? recommended using restricted ISPs, such as Planet Kids and Kidz.net which limit access to pre-approved child-friendly sites, rather than Internet filters.