Schoolchildren could be playing 'virtual truant' – studying social networking websites during lessons instead of what they should be concentrating on – according to experts at IT security firm Global Secure Systems.

In its survey, conducted through Facebook, to discover just how widespread the issue of children visiting sites of this nature at inappropriate times is, 52 per cent of the 1,000 children aged between 13 and 17 who participated confessed that they did so during lessons.

More than a quarter admitted they were visiting social networking sites in excess of 30 minutes a day.

David Hobson, managing director of GSS, said: "I am disturbed, but not surprised, by the findings of this survey.  There are two main issues; one is the safety of youngsters on the web and the second is the time that is frittered away.

"The time youngsters spend on the internet, and more specifically on social networking sites, is a huge challenge for parents and those of us in education.

"I recognise that there is a place for social networking, with a whole new generation now relying on it to communicate, but not at the expense of an education. Schools could learn a lesson from industry and ensure school children productively use the internet."