The Communications Workers of America (CWA) union has filed a complaint against US publishing giant Activision Blizzard.

That's according to Bloomberg, which reports that this was filed with the National Labor Relations Board on September 10th and accuses the games firm of violating US labour law. The CWA says that Activision Blizzard has stifled worker rights and stopped employees from discussing vital information.

“The employer has threatened employees that they cannot talk about or communicate about wages, hours and working conditions,” the filing said.

Activision Blizzard is also accused of telling staff that they aren't allowed to talk about the on-going investigations and even threatening employees with disciplinary action as the result of their activism. That's on top of surveilling legally protected activism and interrogating staff.

This comes in the wake of California's Department of Fair Employment and Housing filing a lawsuit against Activision Blizzard back in July which detailed allegations of a toxic working culture at the Call of Duty maker.