Asda’s £5 ‘thank you’ offer that it launched two weeks ago has driven 1 million customers to its Asda Price Guarantee (APG) website.

The news comes as rival Morrisons today launches its Christmas Collector Card, giving customers the chance to save £25 off their Christmas and New Year shopping.

The promotion runs for eight weeks from October 31 until December 24.  Customers need to spend £40 or more on six seprate occasions, then swap their six till receipts for a £25 voucher.  This can be redeemed against a transaction of £40 or more between December 12 and December 31.

The Morrisons’ Collector Card is now in its fourth year.

It is the latest salvo fired in the grocery price war that has seen Sainsbury’s launch its Brand Match campaign, and Tesco launch its Big Price Drop offer.

Asda’s £5 offer, launched two weeks ago, has helped APG participation surge 150% over the fortnight – its highest rate ever, making it the most successful APG campaign Asda has ever launched.

Every Asda customer who spends £40 or more in store or through in the period October 24 -  November 13 and then checks their bill online at will receive a £5 off voucher, redeemable against their next £40 shop, up to November 24.

Asda Head of Pricing Mark Kupelian  said: “Over one million people in just under two weeks have had the opportunity to see how much cheaper Asda is compared to our rivals through the 10% Asda Price Guarantee.

“The promise to be 10% better value than other supermarkets is the most powerful price commitment in the industry and the additional £5 for checking that commitment online has proved to be extremely popular. We are going to be getting in touch with our millionth customer to ask them to help us celebrate.”