A consumer watchdog has called for tougher government guidelines on supermarket pricing after uncovering tactics it claims are misleading shoppers.

The investigation by Which? into more than 700,000 supermarket prices found "dodgy tactics" which could lead consumers to believe they are getting a better deal than they really are, it says.

Examples of bad practice uncovered by Which? include:

  • Asda doubling the price of a single Muller yoghurt from 30p to 61p when it also offered them at 10 for £4, in order to make the multi-buy look attractive at 40p a pot. The price returned to 30p when the offer ended, meaning the yoghurt cost more per item under the multi-buy offer than a single pot did before or after it was on offer.
  • It also found products sold as "on offer" when in fact they were on sale at the discounted price for so long, that it was no longer an "offer". It found Tesco selling Beck's beer for 190 days on "discount" and 70 days at the higher price.
  • It also found supermarkets increased the price of products immediately before placing them on offer to make the discount appear more significant. Ocado increased the price of strawberries from £3.89 to £4.38 for 13 days. It then sold them stating "was £4.38, now £2.19/£2.29/£2.25" across a 112-day period, although there were nine days during this time when they were sold at £4.38, Which? says.

Which? looked at a year's worth of data to February from independent grocery shopping website Mysupermarket.co.uk and surveyed 1,802 people to find shoppers' responses to grocery offers.

The poll found 39% of consumers said special offers encouraged them to buy products that they did not need, and a third (33%) had bought a special offer they regretted.

A quarter (24%) said they tried to avoid end-of-aisle displays to prevent getting "sucked into" buying special offers.

Government call

Which? says it wants Government guidelines on pricing to be tightened, arguing existing rules designed to ensure special offers do not mislead shoppers left too many loopholes.

Rules state the "was" price should be the amount a product was sold at for 28 consecutive days immediately prior to it going on offer, while a product should not ordinarily be on offer for longer than it was at the higher price.

Which? says the rules include a "get-out clause" allowing for individual circumstances.

Which? executive director Richard Lloyd says: "At a time when household budgets are squeezed and food bills are going up, many people are on the lookout for a bargain.

"It's unacceptable that shoppers are confused into thinking they're getting a good deal when that might not be the case.

"Consumers shouldn't have to worry about whether a special offer is really 'special', so we want the supermarkets to play fair and the Government to tighten up pricing guidelines so that people can shop with confidence."

What the supermarkets say

Asda says: "We are only human and occasionally make mistakes.

"By and large our systems and procedures ensure those instances are kept to an absolute minimum, but when we do get it wrong we put our hands up to say sorry and put things right as quickly as possible."

Tesco says: "We're committed to helping our customers keep their costs down.

"We change millions of price labels in-store and online each week and we sometimes make mistakes, for which we apologise.

"We make every effort to ensure we act in accordance with government guidelines on price promotions."

And Ocado says: "Ocado has thousands of special offers and is committed to providing clear and accurate information about our offers.

"Regrettably on this one isolated occasion this specific promotion did not explain our offer in the required detail.

"Measures have now been put in place to ensure this doesn't happen again and we continue to heavily monitor our processes accordingly."