Children playing the world's most popular computer game are being preyed on by criminals trying to extort money out of them, the police's fraud arm has warned.

Action Fraud has warned that scammers are using Fortnite, an online multiplayer "shoot em up" game with 125 million players worldwide, to trick young players into handing over their parents' bank details.

The fraud reporting centre, which is run by the City of London Police, said it had seen a more than 40 percent rise in crimes involving the hit video game, with victims losing on average £110 each time.

Fortnite, which is certified as being suitable for children aged 12 and over, is set in a dystopian world where most of the Earth's population has suddenly disappeared, living tough conditions and zombie-like creatures to roam the Earth. Players are among the remaining 2 per cent whose job it is to survive and return the earth to normal.

The scam works by convincing players to leave the game and enter a third party website, where they can buy "free" online currency which they can use in the game to buy items like weapons and clothes. To "verify their account is real" players are asked to hand over bank details.