LITTLE ROCK, Ark. – Wal-Mart Stores Inc. CEO Lee Scott led a media charge Thursday to counter criticism that the world’s largest retailer is a behemoth that takes advantage of its workers and stifles competition.

Scott said he wants Wal-Mart workers to know the company was speaking up for them, and he wants Wal-Mart to have a better handle on how it is perceived among members of the public.

The company bought full-page ads in more than 100 newspapers around the nation to highlight its message that it provides opportunity for advancement and that its stores provide mainly full-time jobs that come with a broad benefits package.

“We want to get those myths off the table, set the record straight,” Scott said in a phone interview. He was in New York City for a round of media interviews.

But a union critic of the discount chain said Thursday the company was ignoring social costs created by its megastores. The United Food and Commercial Workers Union said Wal-Mart was bending the truth.

Union spokesman Greg Denier said Wal-Mart may count about three-fourths of its workers as full time, but said those employees don’t get full 40-hour weeks. He said the health insurance the company touts is too expensive and does not provide enough coverage for illnesses that are short of catastrophic.

Wal-Mart has 1.2 million employees in the United States, making it the nation’s largest private employer.