Tesco, Asda, Sainsbury’s, Morrisons, Aldi, Lidl and other large supermarket chains are set to get a major dressing down from officials as the consumer watchdog responds to a super-complaint over misleading promotions.

The Competition and Markets Authority (CMA) will recommend tightening up consumer protection laws but there is expected to be a collective sigh of relief that some of the tougher measures being called for are unlikely to be introduced.

Details are still being finalised, but it appears the CMA has accepted some of the issues raised in the super-complaint filed in April by consumer magazine Which? after a 90 day review.

Recommendations are expected to include larger and clearer on-shelf pricing, consistent across different categories, boosting the role of trading standards officials, and tightening rules around special offers. The number of discounts and offers have soared in popularity across the supermarket sector in recent years, especially due to discounters winning market share from the traditional big four supermarkets.

However, many consumers, and eventually Which?, have complained that the deals are sometimes wrong or misleading.

For example, Sainsbury’s sold Carex Aloe Vera & Eucalyptus handwash at £1.80 for a week, then putting it on “offer” at 90p for 84 days. Generally accepted practice is that products should not be on sale for longer than they were on full price.

At Asda, Uncle Ben’s rice was sold for £1, then the price was raised to £1.58 as part of a “buy two for £3” promotion before being returned to £1 per pack again.

While at Tesco, Easter eggs were said to be “on offer” but the higher price was sold out of season.

In 2013 Tesco was fined £300,000 by Trading Standards for selling strawberries -the second biggest-selling fruit behind bananas across the UK - as “half price” when they had been on the “discounted” price for three months and only full price for seven days.

The CMA is expected to warn that there are examples of misleading practices but not enough to launch a full-scale investigation.

Which? launched its super-complaint under the Enterprise Act 2002, which allows consumer bodies to allege that “any feature, or combination of features, of a market in the United Kingdom for goods or services is or appears to be significantly harming the interests of consumers”.