Schools are to be advised not to place individual photographs of pupils on their websites and to take measures to "anonymise" children's email addresses, under new government guidance to be published today.

Teachers will be asked to ensure that all pupils using the net at school are protected by filtering systems which ensure they do not visit inappropriate websites.

A police officer also warned parents yesterday to move the home computer out of their children's bedroom and into the family living room and not to leave them surfing alone to protect them from potential child abusers.

The details of the Department for Education's new "safer surfing" guidance are to be disclosed as the home secretary, Jack Straw, announced there will be a meeting next week of internet companies, child welfare charities and the police to tackle sex offenders who exploit the 100,000 internet chat rooms available to British children.

A report by the Internet Crime Forum published yesterday urged internet service providers to promote chat services specifically targeted at children and ensure they are supervised with a simple way of reporting any incident in a chat room for investigation.

The forum's chairman, Detective Chief Superintendent Keith Ackerman, said that more than 5m children were now online in Britain and girls aged 13 to 17 were the most likely targets of predatory adult sex offenders who exploited the anonymity of chat rooms. "Too many parents are technophobes," said Mr Ackerman. "The computer is nearly always put in the wrong place - in the kiddies' bedroom. It is then not a family pursuit. The child is to a degree abandoned to look at the internet themselves. Proper supervision in a more public area like the lounge or dining room is required so the parents can learn from the child and vice versa."

The advice to parents will be supplemented today by official guidance to schools working to meet the government's pledge to provide every child with access to the internet and their own email address. The Department for Education guidance will stress the need not to publish individual photographs of named children on school websites and to "anonymise" children's email addresses so that they cannot be individually messaged by strangers outside the school.

This might involve giving each child a numerical email address for use outside the school which translates into an address using their own name when used on a school computer. So somebody who is known to the outside world as "pupil20.4thyear@bashstreet.sch.uk" would be on the school system as "joannasmith.4thyear@bashstreet.sch.uk".

The Internet Crime Forum's report, Chat Wise, Street Wise, published yesterday, said parents need to be educated about the risks of their children using chat room services and it suggests that a kitemarking scheme be introduced to identify sites which are safe for children.