Videogame publisher Activision Blizzard enforced a social media policy that conflicted with workers’ rights and illegally threatened staff in the policy’s enforcement, a government agency said on Monday.

Unless Activision settles, the Los Angeles-based regional director of the National Labor Relations Board will issue a complaint, a spokesperson of the NLRB said in a statement.

The NLRB had been looking into allegations brought to the agency last September by labor union Communications Workers of America.

On Monday in Wisconsin, a small group of quality assurance Activision Blizzard workers voted 19-3 for joining the Communications Workers of America, according to the NLRB.

The union has increasingly focused in recent years on organizing non-union workers in the tech and video game industries.

The “Call of Duty” videogame maker said on Monday the allegations were false.

“These allegations are false. Employees may and do talk freely about these workplace issues without retaliation, and our social media policy expressly incorporates employees’ NLRB rights,” a company spokesperson said.

“Our social media policy explicitly says that it ‘does not restrict employees from engaging in the communication of information protected by law, including for example, rights of employees in the United States protected by the National Labor Relations Act,’” the spokesperson said.

In recent months, Activision Blizzard workers have banded together to try to influence the company’s future, including staging a walkout and circulating a petition calling for the removal of Chief Executive Officer Bobby Kotick. Microsoft announced plans to acquire Activision in January.