Six-year-old twins spent almost £1,000 on in-app purchases while using iPad applications, with some virtual items costing as much as £75 each, as developers and tablet manufacturers face pressure to tighten up restrictions on paid content aimed at children.

Child using iPad
Game developers must ask for credit card details to stop children making in-app purchases, Griffiths claims. (Reuters)

The twins' father, Ashley Griffiths from St. Ives, said they spent £979 on virtual pets and clothing on two separate applications, made possible because they knew the iPad's password, having used the device for homework and playing other games.

Griffiths says application developers should demand credit card details as well as the Apple ID password when downloading in-app content, which is often offered as a way for gamers to speed up their progress through a game, or make playing the game easier.

As a gesture of goodwill Apple has now refunded the money.

The incident comes just days after the Office of Fair Trading threatened to take action against developers who take advantage of the in-app purchasing system, saying it has found evidence of "potentially unfair and aggressive commercial practices," having studied 38 popular titles.

"Children don't understand the value of money, they just see it as a way of collecting more pets and clothes for characters in the games," Griffiths told the Telegraph, adding: "I mean, who in their right mind is going to pay £75 for a virtual pet?"

The OFT's concern has led to the watchdog proposing a set of guidelines for application and game developers to adhere to. These include providing up-front information about the costs of in-app purchases before the game is downloaded, ensuring gamers are not misled and tricked into paying for content - for example when waiting will provide the same content for free - and preventing the use of language that could exploit a child's inexperience.

Controversial among parents and gamers alike, the freemium model whereby games which used to cost several pounds can now be downloaded for free, but then suggest in-app purchases to make the game easier, is here to stay, claims video game consultant Nicholas Lovell.

Protecting children

Speaking at the Wall Street Journal Tech Cafe in London on the same day the OFT published its guidelines, Lovell said children must be protected from games like Disney's Shrek, which he said asks for a payment of 6.99 - with no currency symbol - soon after the game starts.

But he added that the freemium model can be used fairly, and the most dedicated gamers don't use the model at all, revealing that 70% of players who have completed the 400-level Candy Crush Saga spent no money at all on the game.

15-minute window

Griffiths added: "They were just prompted to enter the password, and that's what they kept doing. These games are aimed at children and the designers known exactly what's going to happen. There should be measures in place to prevent this, such as asking for credit card details."

On the iPad and iPhone's iOS operating system, users are asked to enter the password for their Apple ID when purchasing content from the iTunes and App Stores, but by default this password is saved for 15 minutes, during which time it does not need to be reentered.

If an adult enters their password for a child to buy a game, the child could then be left to download expensive in-app purchases for 15 minutes without entering the password again.

This is the case by default, but can be changed in the Settings application. Then go to General -> Restrictions -> Require Password - Immediately.

In March this year, five-year-old Danny Kitchen ranked up more than £1,700 on his parents' credit card buying in-app content for iPad game Zombies vs Ninjas, all purchased during the 15-minute window when the device's password was no longer required.