A fifth of children are going behind their parents’ backs and shopping online without parental permission, according to CPP.

And half of those who buy through the internet are using their own parents’ credit cards to make purchases. What’s worse is that it’s costing British parents as a whole £191m a year.

The research reveals that almost three million kids are using their parents’ credit card details to shop online, making average purchases of about £25, about seven times a year, to get hold of the latest gadgets and computer games from sites such as eBay and Amazon.

Children are becoming increasingly savvy when it comes to taking full advantage of the internet; in many cases they know their way around even better than their parents. And that’s why so many mothers and fathers are in the dark when it comes to their kids’ online habits.

The vast majority of kids (70%) know the sites where their parents shop, and one in five the passwords and usernames for their online shopping accounts. More than a quarter brag that their mums and dads simply don’t know how easy it is for them to use their bank cards on the internet.

The research shows an alarming difference between what adults think they know, and what their children actually do. Only 6% of parents claim their kids have access to their credit card details and only 2% think their children could possibly have made purchases without their permission. Yet not only are kids doing it, they’re often using their parents cards – without getting caught.

Michael Lynch, card expert at life assistance company CPP, said: “We are urging parents to be very vigilant with their bank card details, and to make sure they supervise children’s internet use. Being lax with details online could not only expose parents to sneaky purchases by their children, but also to the dangers of online fraud.

“Web fraudsters are getting increasingly sophisticated and card not present fraud is on the rise. We are advising people to make sure they log out of sites when finished, to check that shopping websites are legitimate and to avoid storing credit or debit card details online.”