A group of employees from Amazon said the company threatened to fire some of them for speaking out about environmental issues.
Amazon Climate Justice Workers said the employees had been told that they were in violation of company policies.
This comes amid calls for the e-commerce giant joined by workers to do more to tackle climate change.
The organization said its employee statement policy is not new and includes all its workers.
In a Twitter post, the group said some employees had been contacted by legal and human resources teams from Amazon and asked about their public comments.
The statement went on to say: “Many employees then received emails that threatened termination if they continued to talk about the company of Amazon.”
Like many other large companies, Amazon has faced growing pressure from both the public and its own employees to take bolder steps to address its environmental impact.
In May, thousands of Amazon employees used the annual meeting of the company’s shareholders to call on chief executive Jeff Bezos to devise a large business climate change plan.
Shareholders rejected this proposal. But Mr Bezos announced plans to completely operate the organization by 2030 and have net zero carbon emissions by 2040, the following September.
More than 1,000 employees left their offices on the day after the announcement to support the Global Climate Strike as well as demonstrate against the environmental policies of Amazon.