Apple in a statement provided by a spokesperson on Friday said it is committed to maintaining "a positive and inclusive workplace" and takes employee complaints seriously.

The National Labor Relations Board has accused Apple of infringing on its employees’ rights to advocate for better working conditions. In a complaint spotted by Reuters, the agency alleges Apple illegally fired an employee who had used Slack to advocate for workplace changes at the company.

The U.S. National Labor Relations Board (NLRB) says Apple is interfering with workers’ rights to collectively advocate for better working conditions by restricting their use of social media and workplace messaging app Slack,

Four Taiwanese employees at Chinese facilities that make products for Apple have been detained by local authorities.

Four employees of the Taiwanese contract manufacturer that makes the Apple iPhone are in detention in China, Taiwanese authorities said Friday.

Taiwan’s government said that they had been accused of a breach of trust, but that their employer, Foxconn, had denied the company suffered any losses.