The prime minister, David Cameron, has been blasted as “ill-informed” and “incorrect” over Sunday trading, by the Association of Convenience Stores.

The claim comes after the government back-tracked on a pre-election commitment to maintain the current regulations.

The government is now planning to devolve decisions on Sunday trading to local authorities.

“There is a strong case for change,” Cameron told the House of Commons after a challenge from Susan Elan Jones, Labour MP for Clwyd South, at today’s prime minister’s questions.

“You’ve got these restrictions on opening hours for many stores that families would like to shop in, and you have to go to these stores and you have to walk around for hours before you’re actually allowed to buy anything,” he said.

“The second point I would make is that you can shop on Sunday. You can shop anywhere on Sunday. You can do it on the internet and I think it’s time to modernise our approach to give families more choice and help create jobs at the same time.”

In response, James Lowman, ACS chief executive, said: “The prime minister has incorrectly suggested that extending Sunday trading hours would create jobs, when recent research by Oxford economists shows a net loss of jobs from longer opening hours for large stores. 

“This is because extending hours would not create any additional consumer spending, so the same trade would be displaced from small to large stores, as we saw during the suspension of Sunday trading regulations during the 2012 Olympics.

“It is disappointing that the Prime Minister has changed his tune since the election campaign, when he stated that he supported the current compromise on Sunday trading.  These plans did not appear in the Conservative manifesto, and the Social Market Foundation has shown how they disregard the prime minister’s own family test.”

David Cameron’s office wrote to the Keep Sunday Special campaign in April this year to confirm the government had no plans to change the Sunday Trading laws. “We believe that the current system provides a reasonable balance,” the letter said.