Tesco has been being ticked off by the Advertising Standards Authority (ASA) for its claims about low prices.

The authority upheld two complaints from rival supermarket Safeway about a national press advert and a leaflet.

The advert said: "Mess for less - no other supermarket is more committed to cutting prices".

The ASA upheld the complaint, agreeing the claim could not be substantiated.

It said Tesco was "committed" to reducing prices, but that Asda had consistently lower prices than Tesco.

'Not 14% cheaper'

Officials also ordered Tesco to stop saying independent research had shown it to be 14% cheaper than Safeway.

The ASA said the way the figures were calculated in the research meant Tesco prices would actually be less than 14% cheaper.

But the ASA found an advert saying Tesco had spent a billion pounds reducing its prices was acceptable.

Tesco said it was "disappointed" by the ruling and was considering an appeal.

It said it had reduced prices by 12.5% over five years, which showed a "unique commitment" to price-cutting.

A spokesman added that the ASA had agreed that Tesco's prices, over the five-week study, averaged at 12.3% cheaper than Safeway.

Escalating war

It is the latest in a series of disputes between the supermarkets as price wars intensify.

In February Tesco announced it was cutting the cost of 15,000 items and claiming total savings of £70m for customers compared with January 2001 prices.

They trumpeted a year of price cuts that had already left the store's shoppers with an extra £200m in their pockets.

But main rival Sainsbury, which lost its number one spot to Tesco in 1995, countered the campaign by saying shoppers should not fall for short-term cuts.