(Reuters) - Walmart Inc likely discriminated against 178 female workers by paying them less, denying them promotions or both, because of their gender, the U.S. Equal Employment Opportunity Commission said in memos seen by Reuters.

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The agency urged Walmart and the women who filed complaints to come to a “just resolution,” which could include a settlement and changes to Walmart’s employment practices, after finding “reasonable cause” to believe there was gender discrimination. The memos were issued in July and viewed by Reuters on Tuesday after they were first reported by the Wall Street Journal.

Bentonville, Arkansas-based Walmart is the world’s largest retailer and the largest private employer in the U.S. with a workforce of 1.5 million.

Walmart told the EEOC it was willing to engage in a “conciliatory process,” though in most cases the agency’s reasonable cause findings were “vague and non-specific,” said Randy Hargrove, a Walmart spokesman.

The cases involved allegations that were more than 15 years old, he said, and were “not representative of the positive experiences millions of women have had working at Walmart.”

Joseph Sellers, a lawyer for the women, said there were at least 1,600 similar complaints pending at the EEOC, accusing Walmart of discriminating against women in pay and promotions between 1999 and 2011. About 150 lawsuits against Walmart, covering the same time period, were pending in federal courts across the country, he said.

In 2011, Walmart convinced the U.S. Supreme Court not to let about 1.5 million female workers complaining about pay and promotions sue in a class action, with a majority of justices concluding the women had too little in common to sue as a group.

Sellers, who represented Walmart workers in that case, said the memos issued in July involve women who worked at Walmart stores in over 30 states. That suggests a broad pattern of pay discrimination rather than isolated instances that could be attributed to local managers, Sellers said.

The EEOC did not immediately respond to a request for comment.

If Walmart cannot reach a settlement with the women, the EEOC could file a lawsuit against the company or authorize the women to bring their own.

Sellers declined to comment on the status of settlement negotiations.