Since last week Amazon has more than tripled the number of chilled and frozen products it is listing on Prime Now, up from 52 to 163.
The retailer has also divided the categories into Dairy & Chilled (was 28 products now 101) and Frozen (was 24 products now 62).
The additional SKUs now means that Asda is now 11.7 percent more expensive than Amazon, up from 8 percent last week.
Morrisons, Sainsbury’s and Waitrose are also all more expensive than the previous week at 15.4 percent, 17.9 percent and 22.5 percent respectively.
However, Ocado and Tesco are more competitive than last week at 19.6 percent and 17.5 percent more expensive than Amazon respectively.
Amazon is the sole or joint cheapest on 114 of the 163 products it stocks (69.9 percent) up from 64 percent last week.
