The makers of "free" web and app-based games have been warned by the Office of Fair Trading of "potentially unfair and aggressive commercial practices" that could target "susceptible" children to pay to continue playing.
It follows cases where children have run up bills of thousands of pounds without their parents knowledge.
Martyn Landi, writer with British-based Apps magazine, says parents concerned about their children running up similar bills should turn off "in-app purchases" on the iPad's settings tab.
How to turn off in-app purchases
To turn off in-app purchases on Google Android devices:
Open the Google Play Store app and select “Menu”, then “Settings”. Scroll to “User Controls”, where you will find the option to “Set or Change PIN”. Click on this and enter your chosen PIN, tap OK and then re-enter the PIN to confirm. Be sure to tick the box next to “Use PIN for Purchases”.
For Amazon Kindle Fire:
Open the Amazon Appstore app and select "Menu", then "Settings". Click "Parental Controls" and choose "Enable Parental Controls" and enter your Amazon password. If you would rather use a PIN, tick the box next to "Use PIN".