About 20% of children aged between eight and 16 have secretly used their parents' credit cards to purchase things over the internet, research has shown.

A survey by life assistance group CPP showed the average child admits making around seven online purchases a year using their parents' plastic - spending an average of £25 each time.

Around 5% of children even admit they splash out on purchases costing between £75 and £150 each time they use their parents' cards to buy things over the internet.

But parents are largely unaware of what is going on behind their backs, with just 2% thinking their children could have made an online purchase without their permission, while only 6% think they have access to their credit card details.

In reality a quarter of children claim their parents do not realise how easy it is for them to use their cards to buy things online.

A further 70% know which websites their parents shop at, while a fifth know their user names and passwords.

Three quarters of children also said they had complete freedom to use the internet unsupervised, despite only a quarter of parents saying this is the case.

And parents are making it easy for their children to buy things online without permission by book-marking their favourite online shopping sites, something 44% have done, while a third have also saved their card details online.

Michael Lynch, an identity theft expert at CPP, said: "We are urging parents to be very vigilant with their bank-card details, which may check any illicit temptation to shop online.

"Being lax with details online could not only tempt children into making sneaky purchases online, but also exposes parents to the dangers of online fraud.

"Web fraudsters are getting increasingly sophisticated, and card-not-present fraud is on the rise."

Copyright © Press Association 2008