The picture may be mixed, and confused by differing strategies on alcohol, but overall the big four are keeping the lid on inflation, says Ronan Hegarty

Never let it be said that our supermarkets can't sniff out an opportunity when they see it - and it seems Asda's rivals think there is capital to be gained from its high-profile commitment to stop selling alcohol below cost.

Asda, it would seem, has been true to its word according to the latest figures from The Grocer Price Index, alcohol prices at the Walmart-owned supermarket are up 2.9% for the month to 31 August.

But while Asda can take the plaudits for putting its money where its mouth is, rivals clearly think they can tempt some of its customers by slashing prices in their own drink aisles.

Overall the alcohol category fell by 1.3% in price during August a figure that is doubly surprising given not only Asda's move but the end of many of the deep promotions that were running during the World Cup in July.

Tesco made the deepest cuts on booze, with prices 3.5% lower in August than during July, while Morrisons wasn't far behind at 3.4%. Sainsbury's cut its booze prices by 0.9% during the month.

In another irony, the bakery category was down 1.9%, fuelled primarily by cuts at Tesco and Morrisons. With widespread speculation surrounding wheat prices following Russia's ban on exports, the reductions give some credence to BRC director general Stephen Robertson's view that the supermarkets are trying as far as possible to keep a lid on inflation. Our figures show the overall price of food measured across over 1000 items did not move for the month to 31 August.

However the picture for the different supermarkets is mixed. Asda, which this week rolled out the second phase of its Price Guarantee advertising campaign, was actually 1.4% more expensive than during July. This increase was balanced out by a 1% fall in prices at Morrisons and a 0.2% decrease at Tesco.

Sainsbury's prices were unchanged overall, while Waitrose, which is not included in the GPI calculations, was 1.1% more expensive than a month ago.

The biggest price increase during August was baby care, which rose 3.8% over the last few weeks, as a spate of promotions came to a close.