A Poundland ad campaign that featured innuendo and depictions of sexual acts has been deemed "irresponsible" by the Advertising Standards Authority (ASA).
The pre-Christmas social media posts featured a "naughty" toy elf and were published on Twitter and Facebook.
One image featured the elf holding a tea bag in a suggestive pose with a plastic doll.
The ASA ruled that this and eight other images breached its code of practice for advertisers.
The regulator pointed out that the images were available on "ungated" websites and therefore viewable by anyone, including children.
Some of the posts may also have been seen as demeaning to women, the ASA added.
Poundland's initial response to the complaints had been to state that the elf campaign was based on humour and double entendres, according to the ASA.
The retailer also pointed out that Twitter and Facebook had policies that were designed to prevent under-13s from creating accounts on the websites.
It also said that a Twitter poll of 12,000 respondents was 82% in favour of the campaign.
"They stated a large number of people found the campaign to be humorous, engaging, and in line with what it meant to be British," the ASA said.
However, the regulator decided against the retailer in the end.
It said that because the ads had been shared widely on social media, they therefore would have been seen by "a large number of people, including some children" who did not actively follow the Poundland accounts.
A 2017 Ofcom report found that nearly a quarter of eight to 11-year-olds now had a presence on social media sites.
The ads were "irresponsible and likely to cause serious or widespread offence", said the ASA, which also revealed it had received 85 complaints about the Poundland campaign.
In December, Poundland removed a box of Twinings tea bags from one of the ads after the tea maker complained that the picture "misuses our product".
At the time, Poundland's marketing director Mark Pym said, "We're proud of a campaign that's only cost £25.53 and is being touted as the winning marketing campaign this Christmas!"
Poundland has been told that the images concerned must not appear again in their current form.
Other new ASA rulings include:
- a ban of a Tunnock's Tea Cakes campaign that featured a female tennis player holding one of the cakes against her thigh. The watchdog said that combining the image with the phrase "serve up a treat" had objectified women and was socially irresponsible
- clearing Ryanair to describe itself as Europe's number one airline. There had been complaints that the claim was misleading in light of thousands of flight cancellations in 2017. But the ASA accepted that travel data for 2016 - the industry's most recent figures - showed Ryanair carrying more passengers than any other European airline