Is Silicon Valley just one giant man cave?

You might be forgiven for thinking so.

The famed tech hub's equal-opportunity credentials took another hit Friday when the US Department of Labor said search powerhouse Google systematically pays its female employees less than it pays men -- a charge the company strongly denied.

"We found systemic compensation disparities against women pretty much across the entire workforce," Janette Wipper, a DOL regional director, testified at a federal hearing, according to The Guardian newspaper, which had a reporter at the event. A department spokesman confirmed the testimony.

The hearing was part of a lawsuit (PDF) filed in January by the department, which has been seeking compensation data as part of a routine audit of Google, a federal contractor.

"The government's analysis at this point indicates that discrimination against women in Google is quite extreme, even in this industry," Janet Herold, a regional solicitor for the DOL, told the Guardian.

Google denied the department's accusations of compensation disparities.

"We vehemently disagree with Ms. Wipper's claim," a company spokesperson said in a statement. "Every year, we do a comprehensive and robust analysis of pay across genders and we have found no gender pay gap. Other than making an unfounded statement which we heard for the first time in court, the DOL hasn't provided any data, or shared its methodology."

During the last few years, critics have been taking aim at Silicon Valley for its bro culture and unlevel playing field.

One 2016 report found that when it comes to women's pay, computer programming is the most unfair occupation in America. Many large tech firms are also grappling with how to increase diversity in the workforce.

Women made up 25.8 percent of Microsoft's global workforce at the end of September, a decline of 1 percent from the previous year, according to a company diversity report released in November. That put it behind such tech giants as Apple, Facebook and Google, but not by much. All three of those companies reported last year that women made up only about 30 percent of their workforces.

It's not the first time the DOL has taken on a tech firm for alleged discrimination. In September, the department filed a lawsuit (PDF) against data miner Palantir for discriminating against Asian job applicants for software engineering positions. Palantir has denied the allegations.

CNET's Steven Musil contributed to this report.

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