Supermarkets have been accused of altering the prices of fruits and vegetables in order to fool customers that they are bagging a produce bargain.

According to an article on thisislondon.co.uk, industry insiders have claimed that Tesco has escalated the cost of popular produce lines to make their price cuts at a later date appear a better deal.

Tesco promises 50 per cent off five fruit and veg lines every week. thisislondon claims that the price of loose, white grapes was raised on November 19 from £3.98 a kilo to £4.99, and that two weeks later the price fell again to £3.99 a kilo. Tesco then launched in-store promotions announcing it had cut the price of white grapes.

A similar tactic has been used on Brussels sprouts, according to the report, Jaffa clementines and, earlier in the year, plums, nectarines, peaches and apples.

A supermarket industry insider said on thisislondon: “This looks like a deliberate attempt to make price savings seem better than they are. It is known in the trade as ‘price establishing’."

Trading standards chiefs say the food stores appear to be taking advantage of a loophole in consumer protection laws. While consumer goods can only be discounted if they have been on sale for 28 days or more, with perishables, the discount only needs to relate to the last advertised price. The ploy used at Tesco is believed to have been used by other supermarkets, according to thisislondon.

Chairman of the Trading Standards Institute, Bryan Lewin, said: “On the face of it, there is a danger that people will be misled into thinking they are getting a bargain when they’re not.”

Tesco said changes to the prices of fruit and veg reflect availability. But a spokesman said he would remove the £1 price cut claim on white grapes, following a reassessment.