Eight of the UK's biggest supermarket chains have agreed to fairer pricing policies, including not inflating prices to make a later discount look attractive. However, Asda is stalling.

Aldi, the Co-op, Lidl, Marks & Spencer, Morrisons, Sainsbury's, Tesco and Waitrose have agreed to adopt the Office of Fair Trading's principles.

Asda says it is "taking time to consider the recommendations in detail".

An OFT investigation, which began in February, found "inconsistency in the way the law was being interpreted and applied". It didn't find supermarkets had breached the law, or were misleading customers.

But there was enough suspicion of bad practice for the OFT to act. Now eight supermarkets have agreed to these principles:

  • Not to artificially inflate prices to make a later discount look more attractive.
  • Discounted prices labelled "was £3, now £2" or "half price" must only be offered at the discounted price for the same, or less time, than the product was initially sold at the higher price.
  • Pre-printed claims on packs, such as "bigger pack, better value", must be true, and there shouldn't be a cheaper way of buying the same volume elsewhere in the same store.
  • That references to previous prices should only be used where they give a relevant basis for comparison. For example, it would be unfair for a supermarket to refer to prices used more than two months previously.

While the agreement is voluntary, however, the OFT says it will monitor supermarkets' practices. Where they don't follow these principles, it says they will "leave themselves open" to enforcement in future.

OFT chief executive Clive Maxwell says: "Shoppers should trust special offers and promotions really are bargains.

"Prices and promotions need to be fair and meaningful. Nowhere is this more important than during regular shopping for groceries, which accounts for 44% of household spending."

Additional reporting by the Press Association.