Sainsbury’s is gunning to win back its least loyal swing shoppers with the trial of a price match on branded products.

The trial of Brand Match launches this week in Northern Ireland in 12 stores, and matches prices with Asda and Tesco on 12,000 grocery items. Prices are checked at the till, and if found to be cheaper at Asda or Tesco, the customer will be given a coupon – capped at £20 – instantly for use at their next shop.

Sainsbury’s group commercial director Mike Coupe said: “We’ve had some challenges with price perception so this is showing our customers that we match the prices, are cheaper or we’ll refund the difference.”

The move follows schemes launched by its rivals. Asda kicked off last year with its Price Guarantee; the grocer now promises to be 10% cheaper on “comparable grocery shopping”. Tesco then launched Price Check. Both schemes require customers to enter receipt numbers online when they get home to check the difference.

Coupe thought Asda “disingenuous” in claiming to be 10% cheaper. “We are using new technology to deliver a price match in real time, making it much more straightforward, rather than customers having to put in a load of data online when they get home, then often not getting around to redeeming the coupons,” he said.

He added: “We’ve copied shamelessly, but we’ve done it better.”

Asda chief executive Andy Clarke was “flattered” by Sainsbury’s launching a similar scheme. Tesco declined to say whether it would extend its Price Check to cover Sainsbury’s – it currently just covers Asda.

Coupe said Sainsbury’s was testing the scheme in Northern Ireland as it was “relatively controlled” and pointed out that some of its rivals had technical problems when launching their price schemes. It will be rolled out if successful.

He said Sainsbury’s data show the grocer matches prices with Tesco and Asda but “thousands of prices move in any given week so we’re just giving customers reassurance”.