ATLANTA — Walmart executives visited stores across the country Tuesday to surprise workers with the news that they had been promoted. The visits were also designed to counter persistent criticism that the world’s largest retailer treats its workers unfairly.

A spokesman said the targeted employees had already applied for the positions and had been interviewed by store managers, but weren’t aware they were in line for more responsibility and pay.

“A lot of people have the misconception that these are just starting-out jobs that don’t pay much and don’t have benefits, and that people don’t last long at Walmart,” spokesman Bill Wertz said.

Much of the criticism comes from the Organization United for Respect at Walmart, or OUR Walmart. The group, funded by United Food and Commercial Workers International Union, consists of employees and supporters who have held protests and promoted strikes against the retailer to press for more work hours, higher pay and more benefits.

When Walmart’s U.S. President and Chief Executive Officer Bill Simon told a conference last month that 475,000 of its 1 million workers were paid at least $25,000 a year, OUR Walmart, and some Democratic lawmakers on Capitol Hill, countered that it also meant 525,000 workers earned less.

The company has since said hundreds of thousands of workers earn at least $25,000.

Despite OUR Walmart’s assertion that the average Walmart associate is paid $8.81 an hour, a figure cited by IBISWorld industry research, Walmart says the average associate earns $12.83 per hour, with 53 percent earning at least $3 more than the federal minimum wage, which is $7.25.

To make its case that it treats employees fairly, the company said 40 percent of promotions last year went to people in their first year with the company and that there are more than 400 promotions a day. It said 75 percent of Walmart’s store management teams started as associates; more than 30,000 assistant managers earn an average of more than $40,000 a year, and more than 4,000 store managers earn an average of $170,000 a year.

Tuesday’s promotion notices are part of Walmart’s plans to promote 25,000 workers in the fourth quarter and 160,000 this year.