Some supermarkets are flouting “pester power” rules aimed at tackling childhood obesity, a report has found.

In a survey, Obesity Health Alliance (OHA) and Food Active found that about a quarter of the 25 stores they visited had put sweets, crisps, fizzy drinks or other so-called “less healthy” foods in prominent parts of the shop, such as close to checkouts or in end-of-aisle displays.

Some supermarket stores “were showing a blatant disregard for the policy and children’s health”, according to the report, Location, location, location, which also found breaches in online sites.

The report comes a year after the government introduced regulations on food promotion and placement in England, which give trading standards or environmental health officers powers to fine large supermarkets if they put some foods high in fat, salt or sugar (HFSS) in prominent locations. The Scottish government has yet to implement any restrictions. In Wales, similar restrictions will only come into force in 2025.

Trading standards officers interviewed for the report said they lacked the resources to inspect shops, while some store managers were unaware of the new regulations.

Despite the breaches, Katharine Jenner, director of the OHA, said that it was encouraging that most supermarkets had taken sweets and sugary treats away from checkouts. “This shows that regulation can help make the healthy choice the easy choice for everyone,” she said. “It also shows that, unfortunately, the food industry will often only follow the letter, not the spirit, of the law.

“This regulation was designed to help take junk food out of the spotlight but, due to exemptions in the policy, too many unhealthy food and drink products remain highly visible both in-store and online.”

The rules only apply to larger retailers with more than 50 employees or in stores larger than 2,000sqft, roughly the size of a tennis court. And there is no blanket ban on particular types of food – some small ice creams, for example, are outside the rules.

“I’m a parent and I’ve really noticed the difference,” Jenner said. “I love the fact that I can just avoid the chocolate aisle and I don’t have my children shouting at me for things. It makes shopping a more pleasurable experience.”

There are signs that the rules have helped people avoid the impulse to buy an unhealthy snack. The Grocer found that sales of healthier impulse foods rose by 5.6% in the first nine months after the changes, while HFSS equivalents remained flat. And sales data analysed by Kantar for the last 12 weeks of 2022 found that a rise of 1.9% in healthier products, while unhealthy sales dropped by 5.1%.

However, obesity remains a serious problem in the UK, affecting nearly three in 10 adults.

The new rules also included bans on some multibuy offers and restrictions on advertising unhealthy food to children on TV, but those measures have been delayed until 2025.

Conservative MPs have railed against the rules and won the delay saying it was unfair to bring them in during the cost of living crisis, despite Public Health England evidence that multibuy offers lead to 22% of people paying more for food than they would otherwise. Jacob Rees-Mogg called for people to move chocolate oranges nearer to checkouts to defy the regulation.

Prof Matthew Ashton, lead director of public health at Food Active, said: “This policy has huge potential to create a healthier environment for our local communities, and this new report shows it has started to have a positive impact by shifting the amount of less healthy options available away from the checkout and other key areas of the store, towards more healthy options being visible.

“But insight with trading standards officers highlights the challenges being faced locally. Insufficient funding combined with competing priorities mean that enforcement of this important legislation is lacking. There needs to be more support for local authorities to ensure retailers cooperate with the legislation and to hold them accountable.”

Dr Kawther Hashem, campaign lead at Action on Sugar, said: “Given two-thirds of adults in the UK are now living with overweight and obesity, one in three suffering from dental decay and the NHS is under considerable pressure, it’s imperative that the government commits to reviewing this legislation regularly, and the exemptions identified in this report, to ensure greater compliance to protect child health.”