More than 400,000 British teenagers have been lured into under-aged casino-style gambling through their video gaming, an investigation has revealed.

The children, aged 13 to 18, have been able to gamble winnings from their video gaming on websites where they can bet them for cash on roulette wheel spins or other games of chance.

The online gambling, which is illegal for under 18s, has been made possible by the creation of virtual items called "skins", modified weapons or costumes that players can win or buy in video games.

Now Parent Zone, an advice service for parents and schools, is demanding urgent action to close the loophole that allows skins to serve as a digital currency that can be gambled and cashed out.

Giles Milton, Parent Zone’s head of content, said its investigation showed gaming firms were not doing enough to stop it: “It is gambling and children should not be gambling online. Parents need to understand what their children are doing with their money.”

There are concerns the trade in skins – of which there are 6bn in circulation worth an estimated £10bn – could itself be fuelling the rise in addictive gaming among teenagers.