Adverts for the gambling website Tombola Arcade have been banned from appearing in the 'I'm A Celebrity, Get Me Out Of Here' app after a regulator found under-18s could see them without restriction.
The ads, part of Tombola's wider sponsorship of the programme, included one headed "Play our Slot Games" and featuring images of masks, an animal skull, vase, compass, map and glass, while another in the 'vote' section of the app offered a chance to win a share of £250,000.
The ads included the text "begambleaware.org" and "18+".
The Advertising Standards Authority (ASA) challenged whether the ads were appropriately targeted.
Tombola said it reviewed the age profile of I'm A Celebrity with broadcaster ITV and its media agency to determine if its sponsorship was appropriate.
Viewing figures for last year's series showed that 91% of the audience was aged 18 and over, and the ads were designed to avoid being appealing to under-18s, Tombola added.
ITV, the publishers of the app, said the programme was broadcast after 9pm due to the potential age-inappropriate content and was not targeted at, or of particular appeal, to audiences aged under 18.
The ASA said marketers should be able to demonstrate that they had taken reasonable steps to ensure that gambling ads were directed at an audience aged 18 and over so as to minimise under-18s' exposure to them.
It acknowledged that the app would be of appeal to some under-18s who watched I'm A Celebrity, but considered that the design, features and content were not directed at those aged under 18.
However it found that there were no mechanisms built into the app to target ads towards, or direct them away from, certain groups of users.
The ASA said: "In the context of an app that was likely to be used by under-18s but which did not have a mechanism through which age-restricted ads could be targeted only to the appropriate age group, we considered Tombola Arcade should not have used the app to deliver gambling ads to consumers.
"We therefore considered the advertiser had not taken sufficient care, through the selection of media, to ensure that the ads were directed at an audience aged 18 and over so as to minimise under-18s' exposure to them."
The ASA ruled that the ads must not be used again without specific targeting to minimise the likelihood of under-18s being exposed to them, adding: "We told Tombola to ensure their ads were appropriately targeted in future."