San Francisco (CNN Business) Four workers who were recently fired from Google are planning to file unfair labor practice charges against the company with the National Labor Relations Board.

The workers will ask the NLRB to conduct an investigation into Google. The filing is expected to be made later this week, according to a representative for the former employees.

Google GOOG The fired workers, Laurence Berland, Paul Duke, Rebecca Rivers, and Sophie Waldman, told CNN Business they believe they were fired from Google for speaking out against the company over its practices, such as having controversial government contracts. They said they engaged in legally protected labor organizing and that they're making the charges because they want to ensure their firings don't scare currentemployees from speaking out.

In response to the claims, Google said it prohibits retaliation in the workplace and that the dismissals were for "repeated violations" of its policies. The workers deny wrongdoing.

"We dismissed four individuals who were engaged in intentional and often repeated violations of our longstanding data security policies, including systematically accessing and disseminating other employees' materials and work," a Google spokeswoman told CNN Business. "No one has been dismissed for raising concerns or debating the company's activities."