Oracle underpaid women and minority workers by $400 million between 2013 and 2016 due to what the US Labor Deparment described as systematic discrimination, the agency said Tuesday.

The company showed "extreme preference" for hiring Asian workers with visas that it could underpay, the department charged.

It also based pay for women and minorities on their prior salaries, a move that helped extend existing wage disparities, it alleged.

Women and minority workers at Oracle workers lost out on at least $401 million in wages from 2013 to 2016 due to what the US Department of Labor described as systematic discrimination on the part of the tech giant.

The enterprise software company intentionally shows "extreme preference" for hiring Asians workers with visas, because doing so also allows it to underpay them, the Labor Department charged in a new filing in its ongoing lawsuit against Oracle.

As a result, the company hires few African-American or Hispanic workers, but when it does, it dramatically underpays both them and women workers as well, the agency said in the filing.

"Oracle has continued to systemically discriminate against employees and applicants based on gender and race," Laura Bremer, a Labor Department attorney, told an administrative law judge.

Dorian Daley, Oracle's general counsel, denied the charges in a statement, calling the Labor Department's lawsuit "meritless" and saying the agency relied on "cherry picked statistics."

"We fiercely disagree with the spurious claims and will continue in the process to prove them false," Daley said.

During the four-year period it studied, the Labor Department found that 90% of the 500 recent college graduates Oracle hired to work in technical positions at its Redwood City headquarters were Asian. Just six of the graduates were black and only five were Hispanic.

Oracle's discrimination added up, the department said

But the company's discrimination extended beyond new hires, according to the reports. The company regularly based pay for women and minority workers on their prior salaries, the Labor Department charged, a move that frequently serves to continue disparate wages between them and white male workers, who are typically better paid. It also frequently pushed Asian, black, and female employees into lower paid positions, according to the filing.

"Oracle's suppression of pay for its non-White, non-male employees is so extreme that it persists and gets worse over long careers; female, Black, and Asian employees with years of experience are paid as much as 25 percent less than their peers," the filing said.

The discrimination added up. Oracle underpaid women in technical jobs at its headquarters by a collective $165 million during the four-year period, according to the filing. During the same time frame, it underpaid Asian technical workers at its headquarters by $234 million, the department said in the filing. It shorted the fewer than 30 black technical workers $1.3 million in the time period, according to the filing.

In addition to the Labor Department suit, Oracle is also facing a class-action suit on behalf of its workers. The plaintiffs in that suit have charged that Oracle paid female workers $13,000 less per year than their male counterparts for doing equivalent work.

The suits against Oracle come amid growing awareness and frustration in Silicon Valley about gender and racial discrimination in the tech industry. Last fall, some 20,000 Google workers took part in a walkout in part to protest pay discrimination against women at the company.