The gambling industry’s spending on marketing surged to £1.5bn last year, prompting renewed warnings about the impact on children, days after a report revealed a steep rise in the number of under-18 problem gamblers.

A study for GambleAware, the UK’s leading gambling charity, found that betting companies have increased their marketing spend by 56% since 2014, with five times more spent online than on TV commercials.

The industry now spends £747m on direct online marketing, £301m through “affiliate” website such as tipsters, £149m through social media and £234m on TV ads.

The £1.5bn total means that gambling adverts account for 8% of the total UK advertising market, which according to market research group Nielsen is valued at £19bn.

It is also more than seven times the annual advertising spend of Proctor & Gamble, the company behind brands including Pampers and Gillette, which is the UK’s biggest single advertiser – and 150 times the £10m that gambling firms give via a voluntary levy to GambleAware, the main recipient of funds for addiction treatment and research.

“Children are growing up in a very different world than their parents,” said GambleAware chief executive Marc Etches.

“Compared to other potentially harmful activities, the rate of gambling among young people is higher than the rates of drinking alcohol, smoking cigarettes and taking illegal drugs.

“This underlines the need to treat gambling as a public health issue.”

The study, by gambling industry specialists Regulus Partners, found that one in eight 11-to-16 year olds follow a gambling company on social media. Those who do are three times more likely to spend money on gambling.

ITV also came under fire this week for allowing a gambling company to sponsor its I’m a Celebrity … Get Me Out of Here app, amid concern that hundreds of thousands of child fans of the show are being “bombarded” with encouragements to bet.

A number of gambling industry bosses have called for a clampdown on advertising over recent months, urging the government to lay down guidelines to protect children.

Paddy Power Betfair said in the summer that it was “supportive of further regulation ... to reduce the volume of pre-watershed TV advertising to protect young children”.

At the same time Philip Bowcock, the chief executive of William Hill, told the Guardian: “Some sort of change is needed, but that has to be led by government. It’s incumbent on them to step up to the plate and have a serious discussion about it.”