Two separate betting shops have been rapped by the Advertising Standards Authority (ASA) this week for targeting children.
Progress Play, which owns m88.com, and TGP Europe, which runs www.fun88.co.uk, have both been hit with bans for promoting animated games in ways that were likely to make them appeal "strongly to under-18s".
Both companies incurred complaints from campaign group Fairer Gambling which questioned whether the graphical content of the shops' ads would make children want to play the games advertised.
The move comes amid an increased focus on gambling firms who target under-18s and concerns from charities like Gamble Aware which claim an increased ad load means more kids are coming into contact with betting shops online.
Recent data from Nielsen indicated that online casino houses have collectively splurged £1.4bn on marketing since 2012; part of a 97% increase in UK ad spend over the past five years.
The bans also come amid MPs calls to treat ads for gambling companies in the same way creative from the tobacco industry is treated.
Games from m88.com – with titles like Fairytale Legends Red Riding Hood, Fairytale Legends Hansel and Gretel and Fairies Forest' – depicted animated folklore characters and settings.
Since being contacted by the ASA, the firm had made the games unavailable for players who weren't members and modified the graphics to exclude any depictions of fairies and other characters like wolves and pixies.
However, despite protestations from the parent firm Progress Play that their graphics were reviewed and it didn't believe they featured any content that was likely to be of particular appeal to children the watchdog disagreed.
Similarly, www.fun88.co.uk incurred a similar ban for promoting games that could appeal to children, including featuring a cartoon white polar bear titled Santa Paws.
The ads must not be shown again in their current form.