Lidl and Iceland have become the first companies to have ads banned after the introduction of rules cracking down on the marketing of junk food in the UK.

The Advertising Standards Authority (ASA) has been policing the ban on ads featuring junk food on TV before 9pm, and in paid online advertising at any time of the day, since 5 January.

On Wednesday the ASA said ads from the two supermarkets that appeared on Instagram and the Daily Mail website had broken the new rules, which prohibit items deemed high in fat, salt and sugar (HFSS) from being promoted as part of the government’s effort to tackle rising childhood obesity.

Lidl Northern Ireland paid Emma Kearney, a popular beauty and lifestyle influencer known online as Baby Emzo, to create an Instagram post promoting the supermarket’s bakery products.

The video post included a tray of pain suisse, a French pastry filled with vanilla cream and chocolate chips, which a complainant to the ASA said was a “less healthy” food product that broke the UK rules.

Lidl said the ad was intended to be “brand-led” – under the new rules companies can run ads promoting their brands as long as they do not show an “identifiable” junk food product – but accepted that the ad did promote a banned individual product.

Iceland Foods ran a digital display and banner ad on the Daily Mail website promoting products including Swizzels Sweet Treats, Chupa Chups Laces, Choose Disco Stix and Haribo Elf Surprises.

Under the new advertising rules, chocolates and sweets fail the nutrient profiling model and are classified as an HFSS product, or “less healthy” food, which cannot be advertised.

Iceland said that while it asked for nutrient profile information from all of its suppliers, it was “aware of gaps” in the data provided.

The supermarket has hired a data provider to compile nutritional information on all products on the Iceland website on a monthly basis, to catch all products classed as “less healthy”, but in this case the ads had appeared on the Daily Mail website.

The ASA upheld the complaints and banned the Iceland and Lidl ads. It told the supermarkets to ensure their digital marketing did not show products that broke the junk food ad rules.