Britain's Office of Fair Trading (OFT) has published a new set of principles to address concerns over special offers and promotions for food and drink, to which eight major supermarkets have agreed to adopt.

The OFT has investigated the ways food and drink prices are displayed, advertised and promoted, to see whether they are confusing customers.

The OFT found inconsistency in ways of interpreting and applying relevant legislation across the food and drinks retail sector, although no breaches of laws have been discovered.

The new principles are designed to make sure discount information are genuine and accurate. For instance, retailers should not artificially raise prices to make a later "discount" look more attractive.

As to signs like "Was 3 Pounds, now 2 Pounds," the "3 Pounds" should be last charged fewer than two months ago in the same store.

Also, if a discount price has been kept longer than the original price, the discount price should turn into the normal price and the label of "discount" should be removed.

For products labeled as "Bigger Pack, Better Value," there should exist no cheaper way of buying the same volume of the goods in the same store. Even if the smaller packs are also on sale, they should not be cheaper than the big packs.

"Prices and promotions need to be fair and meaningful so shoppers can make the right decisions," said OFT chief executive Clive Maxwell, adding that the principles provide supermarkets with a clear benchmark on food and drinks promotions.

The promotions should "reflect the spirit as well as the letter of the law," he said.

Misleading advertising is illegal under the 2008 unfair trading regulations in Britain.

The OFT told Xinhua on Friday that these new principles are only ethical and voluntary, but supermarkets who abide by them can reduce the likelihood of breaching laws.