The ads in today’s papers (26 September) read: “Only one supermarket is… always 10% cheaper.”

The ads run alongside Tesco’s campaign pushing its price cuts.

Asda as dismissed Tesco’s Price Drop as “spin” while Sainsbury’s also slammed the £500m price cutting initiative saying Tesco is “giving with one hand and taking with the other”.

Morrisons is also running press ads to promote its latest Big Pay Day Price Crunch, which also started today, and claims to offer more than 1000 half price offers.

Tesco will be hoping its Big Price Drop will improve margins by boosting sales of own label ranges, as the supermarket sells more brands on promotion than its rivals.

The level of branded goods on sale has risen to 36.5% at Tesco, up from 34% a year ago, according to new research from Assosia, which measures supermarket promotions.

The average across Tesco, Sainsbury’s Morrisons, Waitrose and Asda is 34.3% up from 32.5