British parents grossly underestimate how much time their children spend on the net, suggests a report.
Written by security firm Symantec, it found that UK parents believe their children are online for 18.8 hours per month. The true figure is 43.5 hours.
The report found that British parents were among those with the worst grasp of how long their children are online.
The research also found that in many cases the net was providing a new way for families to communicate.
The Online Living report from Symantec found that 20% of the 6,427 adults questioned had caught their children looking at unsuitable net sites.
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Of the British parents questioned, 81% said they were confident that they knew what they children were looking at online.
By contrast, 31% of the UK children in the survey said their parents did not know what they were doing online.
Cementing bonds
Many of those who caught their children looking at unsuitable material reprimanded them for what they were doing, it found.

Don't give your real name on gaming sites
Best not to have anyone on your IM (instant messaging) list that you don't know in the real world
You can block people in IM and chat areas
Best not to meet people you meet online, they might not be who they say they are
Tell an adult you trust if an online friend asks to meet you
Report a contact to CEOP if you think they might be an adult
"It's not about coming down hard on them when they encounter inappropriate content," said Marian Merritt, Symantec's internet safety advocate in a statement. "The internet is a great place to learn and to play, but there have to be boundaries."
Among all the parents questioned, 75% said they talked to their children about staying safe online.
Around the world about one-third of parents are putting software controls, such as filters, on a family PC to keep children away from inappropriate content. In the UK the number putting controls on a PC rises to 54%.
The survey found that, in many cases, the net is helping to cement the social ties within a family. One-third of the UK children in the survey said they had befriended their parents on a social networking site.