Tesco has vowed to create 20,000 new jobs in the UK over the next two years in a bid to improve customer service.

The retailer said hundreds of stores would be refreshed, with staff given extra training in areas such as fresh produce, fresh meat and bakery. The revamp would also include improving store layout and the overall shopping experience, as well as opening new stores.

Tesco claimed the 20,000 new recruits would be largely made up of local unemployed people, although its figures have been disputed by critics.

The move marks the biggest response to date since chief executive Philip Clarke admitted in January that standards of service and of the overall customer experience in Tesco stores had slipped below the levels he expected. He claimed Tesco stores had been “running hot” for too long, with staff over-stretched and not sufficiently well trained enough.

“At the core of this investment is our determination to deliver the best shopping experience for our customers, bar none,” said UK boss Richard Brasher.

“We will invest in more staff on the sales floor at busy times, greater expertise and help in the crucial areas of fresh food, and enhanced quality and service across our stores at all times.”

But critics urged the government to scrutinise closely the job creation claims.

“I would urge people to take these announcements with a pinch of salt because we’ve been here before,” said James Lowman of the Association of Convenience Stores.

“Between 2008 and 2011 Tesco pledged to create 30,000 new jobs and it turned out they created less than 12,000 new jobs,” he said.

Some analysts questioned how many of the roles were new and how many were the result of existing staff being shifted around.

But Brasher told Sky News: “We are not counting people who move around our business. These are real net new jobs and that’s what we stand behind.”