• Three staffers in Amazon's corporate research and strategy division sued the company alleging gender discrimination and retaliation.
• They claim Amazon regularly assigns female staffers lower job titles for the same roles held by men with higher titles and salaries.

Three Amazon staffers sued their employer on Monday alleging gender discrimination and accusing the company of retaliation after they complained of "chronic pay inequity issues."

Caroline Wilmuth, Katherine Schomer and Erin Combs, who work in various roles within Amazon's corporate research and strategy division, alleged the company assigns female staffers lower job titles for the same roles that are held by men with higher titles and larger salaries. The company then "regularly fails" to promote women, "resulting in the performance of similar work as men in higher job codes for less compensation."

Starting in late 2021, the three women raised these concerns to their managers and Amazon's Human Resources Department, which triggered an investigation into whether the employees were being misclassified due to their gender. Wilmuth said that of the four researchers on her team, three female employees were classified in lower-paid job categories, while the only male researcher was classified in a higher-paid, higher-level role. The male researcher made "approximately 150% of Schomer's salary," the complaint said.

Wilmuth, Schomer and Combs allege that Amazon retaliated against them "within weeks" of their speaking out by demoting them, "severely" reducing their job scope and moving their direct reports to another team that was overseen by a male executive, who they had accused of gender discrimination.

"When I discovered that I was being paid significantly less than men on my team, it stunned and devastated me," Wilmuth said in a statement. "Amazon then made it worse after I complained by taking away the team that I founded and built from scratch — and demoting me to a position that had much less career advancement opportunity."

In March, an investigator assigned to look into Wilmuth's concerns determined that Amazon's decision to shift her reports to another team overseen by a male executive had a "disparate impact" on women, according to the complaint. During the probe, the investigator spoke to the male researcher on Wilmuth's team, who acknowledged the reorganization was "discriminatory, done across gender lines" and harmed Wilmuth, Schomer and Combs.

Amazon spokesperson Brad Glasser disputed the lawsuit, saying in a statement, "We believe these claims are false and will demonstrate that through the legal process."  

He added that Amazon doesn't tolerate discrimination in the workplace, and it investigates all reported incidents of such behavior.

The class-action lawsuit was filed in U.S. District Court for the Western District of Washington. The complaint was filed by Outten & Golden, the same New York law firm that represented a Google executive in her successful gender bias lawsuit, as well as Uber software engineers who sued the company for gender and racial discrimination.

Amazon has faced allegations of gender and racial discrimination from tech and corporate workers in recent years. The company in 2021 opened a review into its employee review system following allegations of racial bias, and a separate investigation into discrimination and bias in its cloud computing unit. Last April, Amazon announced it was conducting a racial equity audit of its front-line employee workforce, led by former Attorney General Loretta Lynch.

WATCH: Amazon partners with Snap to feature shopping ads

Don't miss these stories from CNBC PRO:

• Michael Burry reveals new bet against chip stocks after closing out winning market short
• Warren Buffett's Berkshire trimming holdings, keeping new stock secret
• It's been 2 years since the Nasdaq hit a record and it's gone nowhere since
• Deutsche Bank says this electric flying vehicle stock will more than double in the next 12 months