The Gambling Commission says it will investigate how seven Premier League and Championship clubs had direct links to betting sites from children's pages of their websites.
BBC Sport contacted top-flight clubs Arsenal, Tottenham, West Ham and Aston Villa, plus Championship clubs QPR, Millwall and Reading, to inform them of the links, which contravene the regulatory body's rules.
The links appeared at the bottom of their junior membership and games pages, and have since been taken down.
In some cases the links clicked through to offers of free bets.
But at the time of publication there is still a direct link to West Ham's gambling sponsor on its children's 'colouring in' page which has pictures of a teddy bear, the club mascot and former captain Bobby Moore.