(Bloomberg) -- DoorDash Inc. illegally prohibited office employees from discussing working conditions and fired one because of their organizing efforts, US labor board prosecutors alleged.

The food delivery company threatened to punish staff in Arizona if they took collective action and told them it was illegal to discuss worker conditions on their days off, a regional director of the National Labor Relations Board wrote in a complaint filed on behalf of the agency’s general counsel. DoorDash also engaged in illegal interrogations and surveillance of employees’ workplace activism, according to the complaint, and terminated an employee because they formed an organization, the Service Desk Analysts group, to address working conditions there.

The complaint, filed May 30 and obtained via a Freedom of Information Act request, is the first one the agency has filed against the decade-old company. It accuses DoorDash of “interfering with, restraining, and coercing employees in the exercise of the rights” guaranteed under federal law.

In a statement, DoorDash denied wrongdoing and said it was trying “to ensure the truth is heard” by the labor board. “These allegations are part of a personally motivated attack and entirely without merit,” spokesperson Liz Jarvis-Shean wrote. The company said it was unaware of any union organizing efforts at the Arizona facility and fully respects employees’ legal rights. The terminated employee was dismissed for repeated insubordination, DoorDash said.

Complaints issued by NLRB regional directors are considered by agency judges, whose rulings can be appealed to labor board members in Washington, and from there to federal court. The agency can order policies changed and fired employees reinstated, but lacks authority to hold executives personally liable or make companies pay punitive damages.

Like other app-based gig economy companies, DoorDash classifies its drivers as independent contractors, excluded from federal labor law protections like those enforced by the NLRB. In 2021, the company agreed to pay about $100 million to settle lawsuits alleging its drivers were in fact employees. The company has denied wrongdoing, and has said the independent contractor model provides the flexibility that workers prefer.

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