A new report has called for children to be required to take a "surfing proficiency test" to teach them about the dangers of the internet.

Those who passed the test could be rewarded with more freedom to access the Web than is currently allowed by schools.

At the moment, school PCs often use software that block out sites children could find useful, said the report by the left-wing think tank, the Institute for Public Policy Research.

Damian Tambini, author of the institute's report Communications: Revolution and Reform, launched yesterday by Culture, Media and Sport Secterary Chris Smith, said: "School computers filter out too much information, which leads to frustrated surfers and little else."

Filters that use key words such as 'sex' to spot websites that are unsuitable for minors may also bar children from looking at pages about Essex, he argues.

He warned that many parents were too ignorant of the potential danger of the Net to children and were not doing enough to protect their children.

"Parents mustn't be left to their own devices when it comes to protecting their children from the worst parts of the internet.

"Eleven year-olds should have to take a 'surfing proficiency test' to advise them what to trust on the Net, how to respond to meeting strangers in chat rooms and how to get the most out of the Net," he said.

The report also calls for more effective deterrents for disseminating harmful information to be introduced, including a new offence of deliberately directing harmful content to children.

This would help tackle the problem, for example, of porn barons inserting the brand names of popular toys into a web page search code to boost the number of visitors to a site by attracting children who, for instance, type 'Barbie' or 'Pokemon' into a search engine and unwittingly end up with a list of sex sites.