U.S. agency accuses Activision of threatening and spying on workers during union drive.

Activision Blizzard has violated US labor law by illegally surveilling employees during a walkout and threatening to shut down internal chat channels as a union sought to organize its workers, according to a federal labor agency. The Communication Workers of America union has accused the "Call of Duty" maker of a series of illegal labor practices. Activision is already facing a separate NLRB complaint issued last year claiming the company used a policy limiting what workers can post on social media to bar them from discussing working conditions.