Half of Premier League football clubs have advertised gambling on webpages aimed at, or featuring, under-18s, prompting concern about a voluntary code of conduct drawn up with the help of the betting industry.

A review of gambling regulation published last year resulted in English football clubs avoiding any new government-imposed restrictions affecting their income from betting sponsorship.

Instead, Premier League clubs volunteered to forgo front-of-shirt betting logos from 2026 and also signed up to new rules for sponsorship, drafted in collaboration with the gambling industry’s lobby group, the Betting and Gaming Council (BGC).

The move was designed to show that clubs and gambling companies were acting responsibly, amid concerns about football promoting betting and the impact it could have on young and vulnerable people.

But 10 of 20 Premier League clubs did not appear to be abiding by their own code as of Monday. At least two clubs displayed members of their under-18 squad wearing shirts with betting logos on them, despite being underage.

The findings prompted concern from campaigners including former ITV football commentator Clive Tyldesley and former Conservative leader Iain Duncan Smith about allowing clubs to set their own rules on gambling sponsorship.

The voluntary code, published in July, states that clubs must ensure that “no gambling sponsor logos […] are included on any materials or section of a website which have been designed to be viewed or used specifically by children”.

But betting logos appear on club shop pages aimed at children, under-18 football content and even pages dedicated to “junior” fan forums and mascots, according to analysis by the Guardian and The Pitch Inspection, an online football investigations journal.

Two clubs, Brentford and Wolverhampton Wanderers, included betting logos at the bottom of the kids’ sections of their online merchandise shop.

While the logo on Brentford’s website did not link to the website of its sponsor, Hollywood Bets, anyone browsing the kids section of the Wolves club shop was able to click straight through to its sponsor Debet, which offers casino games and betting on virtual computer-generated sports.

On Everton’s website, a page carrying news about the clubs “junior fans’ forum”, for children aged 11-17, linked to the company’s sponsor Stake.com, as did its under-18 squad page, where two members of the team were seen wearing the online casino firm’s branding on their shirts. Both are under 18 and would not be permitted to wear the logo during a league match.

Everton FC has previously come under fire over its promotion of Stake.com, which specialises in cryptocurrency gambling. In 2022 it asked the sponsor not to use club branding in a row over the gambling firm’s advertising tactics.

A member of Aston Villa’s under-18 squad was also pictured wearing the logo of its sponsor, Betano. The picture has since been removed.

Newly promoted Ipswich Town included a link to 8xbet on its under-18 page, another dedicated to young fans’ initiatives and one dedicated to junior fans’ experiences, including the page where fans sign up to be a matchday mascot.

Multiple clubs, including Liverpool, Chelsea and Leicester City, linked to betting sponsors from pages dedicated to under-18s football.

Pages on the Chelsea FC website that list under-18 fixtures, as well as one displaying youth team highlights, featured links to the website of their sponsor Betway.

Liverpool, Everton, Chelsea, Aston Villa, Wolves, Leicester City, Brentford and Ipswich removed links or images after they were contacted by the Guardian. Betway said it had “zero interest” in marketing to under-18s and had notified Chelsea of the issue.

As of Wednesday afternoon, Newcastle United’s website still linked to three betting sponsors’ websites on pages for its under-18 squad and its academy, aimed at children as young as nine.

And Nottingham Forest’s website displayed branding and links to the club’s gambling sponsor, Kaiyun Sports, on a section of the website dedicated to the girls academy, a programme for those in the under-10 to under-16 age group.

Tyldesley said: “I’d like to say that I’m surprised but I’m not. We are coming across more and more examples of how we cannot rely on operators, football clubs, TV channels to regulate themselves.”

Duncan Smith, who co-chairs a parliamentary group examining gambling harm, said: “The problem with codes of conduct with the gambling industry is they just ignore them and carry on damaging lives.”

In September 2022, Betway was fined more than £400,000 after its logo was found on a page of the West Ham website where young fans were invited to colour in a teddy bear.

Charles Ritchie, of the campaign group Gambling With Lives, said fresh concerns about gambling logos attached to content aimed at minors indicated that “nothing’s been learned”.

“The gambling industry continues to use football clubs to ensure young fans are just a click away from harmful products,” he added.

All of the logos and links reviewed by the Guardian and The Pitch Inspection appeared on the header or footer section of club websites, which are reproduced on every page.

However, several clubs including Manchester United, had ensured gambling links were removed from those pages that could appeal to children.

The Premier League said it was working with clubs to implement the code and that the Independent Football Ombudsman would consider unresolved complaints.