Police and cyberliberty advocates expressed a continuing need for tangible evidence of Internet child abuse on Tuesday before a more proactive approach will be taken in Britain to crack down on Net paedophiles. The Internet Crime Forum (ICF) report, published on Tuesday, revealed that one in five of the 4.8 million children online in the UK have been approached by paedophiles in Internet chatrooms. Despite a steady increase in the number of cases where the Net has facilitated sex offences against children, police and cyberliberty groups still say that evidence of these crimes in Britain is too marginal to demand immediate action. "We [Hampshire police force] have seen several cases of contact where regrettably sexual activity has taken place," said detective chief superintendent Keith Ackerman. But he said the evidence was not substantial enough to prove the need for a more proactive crackdown on Internet paedophiles. "Unless there is something overt in their conversation making it obvious to an independent party that they have criminal intentions, most of the conversations will be innocent," he added. Cyberliberty activist Malcolm Hutty, director for the Campaign against Censorship of the Internet in Britain, contributed to the ICF study, but warned against attempts to quantify the risks posed by Internet paedophiles. "The number of [Net paedophile] cases is in the margins of error -- they are really anecdotal -- the statistics are not possible to quantify," he said. Uniform crime figures do not record any distinction between online and offline cases, hampering efforts to make an accurate assessment of the level of sexual approaches British children receive in chatrooms. Furthermore, many Internet paedophile incidents fail to bring about successful criminal charges in the UK, and so go unrecorded. In America, however, the FBI, Customs, and Postal Inspection Service have secured more than 2,000 convictions since 1995 for offences involving child pornography or the sexual soliciting of minors on the Internet. "We can see from America that there's no reason to be complacent about this in Britain," said John Carr, Internet consultant for NCH Action for Children. "Even though there are a small number of cases recorded in the UK so far, they are definitely moving in one direction, and that's the wrong direction," he added. "One victim is too many," said learning and technology minister Michael Wills on Wednesday at the launch of his revised Superhighway Safety guidelines for schools. Television broadcaster Carol Vorderman has worked with the child victims of many Net paedophile cases, including the 13-year-old girl who was raped by Patrick Green last year. "The victims I have spoken to will often say that they are not an isolated case," she said. "Many children don't tell their parents what's going on. This is exactly what paedophiles do -- they earn the child's trust and then abuse the child, which is how they've protected themselves for years." At the Internet Watch Foundation's (IWF) first parliamentary meeting in the House of Lords in January, Home Office minister Lord Bassam said the policing of Internet paedophiles would be a "top priority" for the new High Tech Crime Unit due to start work in April. At the ICF meeting on Tuesday, however, Ackerman was less optimistic about the cybersquad being assigned to Net paedophile cases. "We're encouraging every police force to have an ability to investigate such cases themselves. We will need to balance Internet paedophile cases against their circumstances, and assess its merits," he said. What are the risks of paedophiles approaching my children through Yahoo! Messenger chatrooms? Find out the details of ZDNet News' investigation in the Chatroom Danger Special Report Are your children in danger on the Internet? Find out with the Web of Porn Special Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read other letters.