Asda, Morrisons and Iceland have been named as the "worst offenders" for undermining parents' efforts to feed their children healthily, according to the Children's Food Campaign (CFC).
Yet, not one "traditional format" supermarket in the survey had any healthy food options promoted at its checkouts, the report underlined.
While these three supermarkets were top of the list for displaying unhealthy food or drink at more than 80% of their checkouts, the CFC also criticised the Co-operative, Sainsbury's, Tesco and Waitrose for making families queue past displays of unhealthy snacks to reach the tills.
Sasha Watkins, registered dietitian and spokesperson for the British Dietetic Association, said: "We all know how hard it is to steer our loved ones in a healthy direction without having to queue past brightly coloured snacks targeted at children. Studies have found that having food within easy reach is more likely to tempt us and parents also have to contend with the added factor of ‘pester power’."
The author of The Food Coach blog added that mums are already struggling to keep their kids' calories under control and this is another unhelpful hurdle for families.
"Sweets and chocolates are just ‘empty calories’ as they contain high levels of sugar and fat but no other good nutrients like vitamins, minerals or fibre," Watkins told HuffPost Lifestyle
She added that a recent survey demonstrated the UK population continues to get too much of its energy intake from added sugar, of which confectionary is a key source.
"This is exactly the type of calorie intake supermarkets should not be promoting if we want to win the battle against the bulge."
The Checkouts Checked Out report found that most supermarket branches and high street stores routinely promote unhealthy snacks at their tills and in their queuing areas, despite several promising to reduce the practice - and in many cases, sweets and crisps were positioned at children's eye level.
The trend had also spread to smaller stores and non-food retailers including HMV, New Look, Superdrug and WHSmith, which all displayed sweets and chocolates in the queuing area near the checkouts, the CFC said.
Just one supermarket, Sainsbury's, confirmed a policy of not selling "impulse confectionery" at their main checkouts, but added they did display "gifting confectionery or seasonal lines".
Netmums founder Siobhan Freegard said: "Parents daren't take their eyes off their kids for a minute in case they get into trouble and now it seems we need to keep a constant eye on retailers too.
"In the last 10 years we have made so much headway in the battle against junk food with clearer on-pack labelling, but when it comes to the simple issues of junk food on display by the checkout we are back to where we started.
"Stores must stop working against mums and dads and work with us."
