MOUNTAIN VIEW — Already fighting a federal probe into alleged pay discrimination against women, Google on Thursday was sued by three female ex-Googlers claiming the search giant systematically pays women less than men and has a “sexist culture.”

Women are “segregated” into lower-paying jobs and career tracks, hampering their advancement, while men with equivalent qualifications race ahead, the suit claims.

“This is not just about three women trying to get money, this is about three courageous women stepping forward to change the company, to help women in the future and to change the Valley as a whole,” said the women’s lawyer, James Finberg.

The legal case will play out as Silicon Valley continues to wrestle with its treatment of women, from a lack of diversity among leaders and workers at tech companies to allegations of sexual harassment. Google, where women make up only 31 percent of the global workforce and hold just 20 percent of technology jobs, is fighting the U.S. Department of Labor in court, seeking to withhold salary data it argues is private but that the department is demanding for its probe into alleged pay discrimination against women.

Thursday’s legal action by the three employees seeks class-action status to cover all women employed by the Mountain View search giant in the past four years.

“It was time to stand up and say, ‘This isn’t OK, this isn’t fair, and no more,’ ” said plaintiff Kelly Ellis. “It really feels like a good time to be bringing this lawsuit, because people are waking up to the fact that sexism is pervasive and real in Silicon Valley and in the technology industry.”

Finberg said Thursday that his legal team would rely heavily on testimony from U.S. Department of Labor hearings, which showed “statistically significant (compensation) disparities adverse to women across the board.”

The labor department has called pay discrimination against women at Google “extreme.” Google’s vice-president of HR, Eileen Naughton, has countered that the firm’s own annual analysis has shown “no gender pay gap.”

Google will review the suit in detail, but disagrees with the “central allegations,” company spokeswoman Gina Scigliano said Thursday.

“We work really hard to create a great workplace for everyone, and to give everyone the chance to thrive here,” Scigliano said. “Job levels and promotions are determined through rigorous hiring and promotion committees, and must pass multiple levels of review, including checks to make sure there is no gender bias in these decisions.

“And we have extensive systems in place to ensure that we pay fairly. But on all these topics, if we ever see individual discrepancies or problems, we work to fix them,” Scigliano said.

According to the lawsuit, filed Thursday in Superior Court in San Francisco, Google continues to “channel and segregate” women into lower compensation levels and “less-favorable” career tracks. Fewer women than men are promoted, and those promotions come more slowly, the suit claims.

“The net result of this systemic discrimination is that Google pays women less than men for comparable work,” the suit alleges.

The issues addressed in the suit apply across most of the technology industry, said Adriana Gascoigne, CEO of the non-profit Girls In Tech.

“There is a systemic problem where women are getting paid less than their male counterparts for doing the same exact job, because employers can get away with it,” Gascoigne said. “I’m glad that these women are coming forward and holding this tech giant accountable because it needs to happen in order to create change.”

Finberg said about 90 women have approached his firm about pay discrimination at Google. Other evidence to be brought forward against the firm includes a New York Times report on employee compensation that was based on a former employee’s data set, Finberg said. That report suggested that at most salary levels, women at Google receive lower pay and smaller bonuses than men. Google has said that its own analysis, which included location, tenure, job role, level and performance, showed women made 99.7 cents for every dollar a man made, a statistically negligible difference.

Ellis said in the lawsuit that she started at Google as a software engineer in May 2010 but quit about four years later, “because of the sexist culture at Google.” Coming into the job, she was put at “Level 3” compensation, which is ordinarily for software engineers fresh out of college, despite her four years’ experience, the suit claims. Men with equal or weaker qualifications were placed in the higher-paying “Level 4,” the suit alleges.

Ellis was eventually promoted to Level 4, “but by that time, her male counterparts were on their way to even higher levels and compensation for similar work, ensuring that she could never catch up on the gender pay gap,” according to the suit.

Another plaintiff, Holly Pease, was hired in 2005 as a corporate network manager, with a decade-long history as a network engineer, the suit says. She managed about 50 software engineers and analysts, most of them on “technical” job tracks, but she was classified into the “non-technical” business-systems track, where salary, bonuses, raises and company equity are lower, the suit claims.

The third plaintiff, Kelli Wisuri, arrived at the company in October 2012 when Google bought the company where she worked. She had more than two years’ experience in sales, but was placed in the lowest compensation level for full-time, permanent workers — Level 2 — even though men with equivalent qualifications would start at Level 3 or higher, the suit says.

Wisuri quit in January 2015, she says in the suit, “due to the lack of opportunities for advancement for women at Google.”

The suit seeks unspecified “wages due” and damages, plus a share of Google profits from “its unlawful and/or unfair business practices.” It also demands Google stop paying women less than men for equivalent work.