According to addiction experts in the UK, these type of games encourage teenagers to think gambling is harmless fun.
Children are using 'virtual coins' to imitate the thrill of hitting the jackpot with slot machine and roulette games on their home computers and mobile phones, the 'Daily Mail' reported.
At present Facebook provides hundreds of virtual slot machine and poker games, including Jackpotjoy, Slotomania and DoubleDownCasino.
Zynga, which accounts for 12 per cent of all Facebook's revenues due to its popular games such as FarmVille, has also launched Zynga Slots in the UK last month.
Facebook has three million UK users aged between 13, which is the lower age limit for registration, and 17. But a further one million are estimated to be under 13 and pretending to be older.
The legal age for gambling in Britain is 18. Dr Carolyn Downs, from the University of Salford, was warned when her 13-year-old daughter became upset at losing virtual money on the game 'Fluff Friends'. "It's well-established that the younger the children start
gambling, the more likely it is they will become habitual gamblers and also problem gamblers," she said.
"It's a long-term, life-long risk. What we're doing is setting up these kids to be problem gamblers as they go through life," she was quoted as saying by the paper.
Although the gambling games are free, users are encouraged to spend money if they want to keep gambling or increase jackpots.
A UK-based charity, GamCare wants the Gambling Commission to investigate social gaming.
"This is a really rapidly-moving area. We need to think through very carefully any risks that it presents particularly for young people," Policy and development director Mandy Barrie said.
"There is a link between early exposure to gambling and developing a problem in adulthood," he added. The Gambling Commission is 'monitoring developments' with regard to virtual gaming which it believes to be 'at the perimeter of current legislation', the paper reported.
A Facebook spokesman said, "In addition to complying with local law, all applications on Facebook are required to operate within the bounds of our developer guidelines."
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