CHICAGO (Reuters)—Former Wal-Mart Stores Inc. warehouse workers of Cuban origin may pursue a lawsuit accusing the world's largest retailer of discrimination and of firing them when they complained about their treatment.

Monday's ruling by a federal judge in Chicago came as Wal-Mart awaits a U.S. Supreme Court ruling on whether more than 1 million female workers can continue pursuing the largest class action gender bias case in history against the company.

In the case of the Cuban workers, Rolando Padron, Bobirt Miranda and Eusebio Calzada accused Wal-Mart last October of paying them less and giving them different work schedules than non-Cuban workers and denying them "make-up" days.

The men, each of whom had worked for Wal-Mart for more than five years, also said their supervisors ignored a half-dozen complaints before firing them in November 2006 in retaliation. They filed charges with the U.S. Equal Employment Opportunity Commission, which found reasonable cause for a lawsuit.

Wal-Mart sought to dismiss the case, saying the men had no grounds to pursue a class-action case on behalf of Cuban warehouse workers nationwide and had waited too long to sue.

While agreeing with most of Wal-Mart's arguments, U.S. District Judge James Zagel allowed the plaintiffs to pursue a claim under federal civil rights law alleging discrimination on the basis of ethnic characteristics.

Judge Zagel rejected Wal-Mart's argument that because the EEOC charges were based on national origin discrimination and not racial discrimination, "the essence" of the plaintiffs' claim could not be discrimination based on ethnic characteristics.

"Plaintiffs allege that they have dark-colored skin, eyes and hair and that they are members of a racial minority, which could give rise to an inference of racial animus," the judge wrote.

Wal-Mart spokesman Greg Rossiter said: "We're pleased the court has dismissed important aspects of the case and we strongly disagree with the claims."

He also said the Bentonville, Ark.-based company has strong policies against discrimination.

A lawyer for the plaintiffs did not immediately return a call seeking comment.

The case is Padron et al. vs. Wal-Mart Stores Inc., U.S. District Court, Northern District of Illinois, No. 10-06656.

A ruling in the Supreme Court gender bias case, Wal-Mart Stores Inc. vs. Dukes, is expected by the end of June.