Google employees have accused their employer of creating a surveillance tool disguised as a calendar extension designed to monitor gatherings of more than 100 people, a signal that those employees may be planning protests or discussing union organizing. Google parent company Alphabet “categorically” denies the accusation.

The accusation, outlined in a memo obtained by Bloomberg News, claims severe unethical conduct from high-ranking Google employees, who they say allegedly ordered a team to develop a Chrome browser extension that would be installed on all employee machines and used primarily to monitor internal employee activity. Employees are claiming the tool reports anyone who creates a calendar invite and sends it to more than 100 others, alleging that it is an attempt to crackdown on organizing and employee activism.

The existence of the in-progress software tool was discovered in September, Bloomberg reports, after employees on the privacy review team flagged it over “concerns” with how it squared with company culture. Later, in October, employees began discussing the tool with others after learning it would be forcibly installed on company machines and would not be removable. The tool earned even more scrutiny after some employees were barred from accessing documentation about the project.

Google claims the extension is a harmless internal tool to fight calendar spam

Alphabet denies the accusations, and claims the product has been in the works for months and underwent standard legal, privacy, and security review. “These claims about the operation and purpose of this extension are categorically false. This is a pop-up reminder that asks people to be mindful before auto-adding a meeting to the calendars of large numbers of employees,” a company spokesperson tells Bloomberg. The company also claims the tool does not report identifiable information to Google about employees creating invites and doesn’t stop those invites from going out, but is instead designed to help cut down on calendar spam.

The relationship between Google leadership and employees has grown increasingly contentious in recent years, following high-profile episodes like the firing of anti-diveristy memo author James Damore, the company’s stance on controversial government contract work and courting business in China, and last year’s massive Google walkout over the company’s handling of sexual harassment.

Since 2016, employees have slowly nurtured an effective and mobilized activist coalition within Google to better hold leadership accountable and to enact change, on a scale previously unheard of in Silicon Valley and in ways that have since been adopted across the tech industry.

Earlier this week, Google management in the company’s Zurich, Switzerland office tried to shut down an employee-led talk on unionization by cancelling the event and offering to host its own discussion on labor laws, but the initial meeting happened anyway. Last month, Google contractors in the company’s Pittsburgh office voted to unionize with the United Steelworkers union, with the process now moving to the bargaining stage.