New statistics compiled by the Gambling Commission show the number of eleven-to-16-year-olds affected has quadrupled during two years to 55,000.
The Bishop of St Albans, Rt Rev Alan Smith said: "Today's findings by the Gambling Commission make worrying reading and serve as a warning to parents.
"After years of progress, it seems the rates of children gambling are creeping back up.
"We need to start taking the dangers of gambling seriously - 55,000 children classed as problem gamblers is a generational scandal."
According to an audit due to be published on Wednesday, 70,000 youngsters are considered at risk of becoming problem gamblers.
Seen by the Daily Mail, it concludes 450,000 kids are illegally using things like fruit machines, bingo and betting shops regularly - equating to one in seven aged between eleven and 16.
The audit found they spend £16 on average every week.
Bishop Alan continued: "However much the gambling industry says it is not targeting the young, it is clear that a significant minority of teenagers are still being drawn into gambling and it is no coincidence that one-in-six children have seen gambling adverts on social media.
"In-game gambling and loot-boxes are a new phenomenon and so require new answers.
"The world has changed since 2005 when the gambling sector was deregulated and so, sadly, has gambling.
"Therefore, government, local authorities, schools, the private and the charitable sector need to study these findings carefully and put in place preventative measures to safeguard young people."
Last month, Bishop Alan said he was "absolutely appalled" at the delay to a crackdown on high stakes betting machines, dubbed the "crack cocaine" of gambling.
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