By Julia Love

SAN FRANCISCO (Reuters) – Apple (NASDAQ:) has restricted employees’ use of workplace messaging app Slack, hampering workers’ ability to engage in protected speech and organizing, a former employee alleged in a complaint to a U.S. labor regulator filed on Tuesday.

Slack, which allows individuals to create on-the-fly group conversations, was rolled out a few years ago by Apple and has become increasingly popular as a discussion forum during the pandemic, multiple employees have said.

Apple employees who advocate for pay equity, remote work and other causes in the company have used it as well. On Oct. 25, according to the complaint by former worker Janneke Parrish to the U.S. National Labor Relations Board, Apple introduced moderation rules for the platform.

“It gives the appearance of surveillance of employees’ protected speech activities,” said the complaint, a copy of which was reviewed by Reuters.

An Apple spokesperson declined to comment. The company has previously said it does not discuss specific employee matters but is “deeply committed to creating and maintaining a positive and inclusive workplace,” taking “all concerns” from employees seriously.

Apple’s policy holds that workers cannot create new Slack channels “without management’s knowledge and support,” according to the complaint, which includes a screenshot of a message detailing the policy.

Posts about workplace concerns must be directed to a manager or the “People Support” group, according to the complaint.

Parrish says she was fired in October after playing a leading role in employee activism.

The charge comes amid a broader push by Silicon Valley workers to speak out about their working conditions and the impact of technology on society. The employee activism has been particularly striking at Apple, which is known for its secretive culture.