Grocers Asda and Sainsbury’s have instantly hit back at rival Tesco’s new Price Promise promotion and questioned the quality of the UK’s largest grocer’s new marketing push.

Asda will this week release a smartphone app which will chop the time it takes to compare the price of a shop at Asda with its rivals.

The app, released on Saturday, will present shoppers with a new, simplified version of its Asda Price Guarantee (APG) app which will allow them to compare the price of a basket in 11 seconds. Asda said the shortest time a customer could take using the previous app would have been 25 seconds.

The APG promotion had been criticised by rivals and commentators as being laborious for shoppers.

An Asda spokeswoman said its promotion was a stronger offer than Tesco’s Price Promise which offers shoppers coupons up to £10 for the difference in price if a comparable shop would have been cheaper at its rivals.

She said: ‪“With the Asda Price 10% Guarantee our promise is to beat prices, not just match them.”

Asda said it had this week reached the landmark of 50 million shoppers who had checked whether their shop would have been cheaper elsewhere on its APG website since its launch in 2010.

Tesco launched the Price Promise promotion in England, Scotland and Wales yesterday following a trial in its stores in Northern Ireland in recent months. It said the offer is “industry-leading”.

Sainsbury’s also questioned whether Tesco’s promotion will offer anything new to shoppers in the fiercely competitive grocery market.

A Sainsbury’s spokesman said: “They are playing catch up.

Sainsbury’s launched Brand Match 18 months ago. It compares around 14,000 product prices every day with prices at Asda and Tesco, including promotions, and has benefited millions of our customers.”

He added: “It’s just one part of our work to ensure Sainsbury’s customers get a good deal, which also includes targeted and meaningful offers, whether that’s direct mail, a coupon at the till, or the Nectar loyalty programme.”

Morrisons also offers coupons at till using its Catalina voucher system which produces money-off vouchers for shoppers based on their purchases. Morrisons declined to comment on Tesco’s promotion.