The U.S. Department of Labor has raised concerns that Google's strict confidentiality agreements have discouraged employees from speaking to the government about discrimination as part of a high-profile wage inequality investigation.

Following a judge's ruling that Google must hand over salary records and employee contact information to federal regulators investigating possible systemic pay disparities, a labor department official said the agency was worried that the technology corporation's restrictive employee communication policies could impede the next phase of the inquiry.

"We have had employees during the course of the investigation express concerns about whether they are permitted by Google to talk to the government, because the company policy commits them to confidentiality," Janet Herold, labor department regional solicitor, told the Guardian in an interview after the judge's order.

"When even a single employee expresses that, that means many more people are too concerned to make the call or have the conversation. The chilling effect is quite extreme."

Google strongly rejected Herold's claims, saying in a statement: "Our workplace policies are clear that employees can talk freely about workplace matters, and report concerns to the government without any fear of repercussion."

But Herold's comments and the DoL's recent filings -- along with interviews with former Google workers and a separate federal complaint against the company -- paint a picture of a workplace where employees have allegedly been subject to overly broad and illegal confidentiality policies and threatening messages from managers that have intimidated them into staying silent about wrongdoing.

These kinds of confidentiality clauses are commonplace in Silicon Valley, ostensibly to protect trade secrets. But critics say the rules are sometimes so extreme they prevent employees from engaging in their legally protected rights to raise concerns about discrimination, sexual harassment and other labor violations.

"It is built into the culture that it's shameful to leak," said one former senior manager at Google, who requested anonymity for fear of repercussions. "It builds a sense of paranoia … There is just such a sense that leakers will be found and terminated."

The concerns of Herold and other government attorneys stem from the labor department's continuing audit of Google, which is a federal contractor and must comply with equal opportunity laws. In January, the labor department sued Google for compensation data it refused to disclose after the government's preliminary inquiry found that the company pays women less than men across the board.

Google -- which argued that the data requests were too expansive and violated employees' privacy -- has vehemently denied the discrimination allegations, saying its own analyses have found there is no gender pay gap.

A judge ruled last week that Google must provide the labor department with 2014 salary records and contact information for up to 8,000 employees for possible interviews. Herold said the department was concerned that the next phase of the investigation could face obstacles as a result of Google confidentiality rules.

"The entire enforcement mechanism of federal law is dependent on employees feeling free and able to talk," she said. "In a case like Google, where our preliminary analysis reveals systemic and sweeping discrimination in pay against women for nearly all job titles -- something is going on and we need to find out what that is. Employees are the eyes and ears on the ground."

A Google spokesperson responded in a statement: "Assuming the decision becomes final, of course [the labor department will] be able to contact and speak freely with the identified set of employees, as outlined in the decision." Google also noted that the judge's ruling criticized the labor department, saying it had "not taken sufficient steps to learn how Google's system works" and appeared to have "an animus that is difficult to understand."

But Herold argued that by seeking to discredit the department, Google was further discouraging workers from trusting regulators: "I'm concerned they're trying to convince people not to talk to the government."

The labor department's concerns are bolstered by a separate complaint the National Labor Relations Board (NLRB) filed against Google in April, alleging that the company's confidentiality rules infringe on employees' rights. Google has allegedly "threatened employees with termination and legal action for engaging in protected, concerted activities."

The charges stem from a Google product manager's civil suit alleging that company policies -- broadly defining "confidential information" to mean "without limitation, any information in any form that relates to Google or Google's business and that is not generally known" -- have restricted employees from speaking internally about illegal conduct or dangerous products and prohibited them from speaking to the government, lawyers or the press about wrongdoing.

A Google spokesperson noted that the company's human resources handbook states: "Nothing in the Google policies -- limits employees' rights to (1) talk about pay, hours, or other terms of employment or working conditions, or (2) to communicate with a government agency or official regarding those topics or any violation of law."

The spokesperson also said "the policies at issue had already been revised and replaced well before the NLRB filed its complaint," but did not respond to questions about how the rules had changed.

The charges about confidentiality have been dismissed in the product manager's suit while the NLRB is reviewing similar claims, but there has been no ruling on the merits.

The confidentiality policies and the way Google teaches and enforces them can have a negative impact on employees on a regular basis, said the former manager.

"I would sort of second-guess myself about sharing anything about my day at work," the former manager said, adding that the policies could be particularly hurtful to people who were mistreated and wanted to speak out but were too afraid.

Another former Google employee, who worked in a product role, said many were discouraged from raising concerns out of fear of retaliation. "It's a situation of speak up and watch nothing happen, or speak up and watch it backfire."

One Google director warned employees about the risks of leaking in a staff email last year -- which was leaked to the press: "If you're considering sharing confidential information to a reporter --or to anyone externally -- for the love of all that's Googley, please reconsider! Not only could it cost you your job, but it also betrays the values that makes us a community."

Labor department investigators are not the only ones who say they have encountered Google employees hesitant to talk.

James Finberg, a San Francisco-based attorney, said he had been in contact with Google employees concerned about pay disparities amid the labor department investigation. He said he was considering a lawsuit, but that some workers had raised fears about confidentiality.

"They're worried about termination," he said. "Google consciously does that to thwart litigation."