Hundreds of Amazon employees criticised the company’s record on climate change despite their jobs being at risk for speaking out.

More than 340 employees signed an online protest, organized by an advocacy group founded by Amazon workers called Amazon Employees For Climate Justice. Amazon had sent letters to its members threatening to fire them if they continued to speak out.

“It’s our moral responsibility to speak up, and the changes to the communications policy are censoring us from exercising that responsibility”, an employee said.

“While all employees are welcome to engage constructively with any of the many teams inside Amazon that work on sustainability and other topics, we do enforce our external communications policy and will not allow employees to publicly disparage or misrepresent the company or the hard work of their colleagues who are developing solutions to these hard problems”, an Amazon spokesperson said.

The company relies on fossil fuels to power the vehicles that ship its packages. It said it has already pledged to become net zero carbon by 2040 and that the policy is not directed at any specific group. However, its employees have often been protesting about some of its practices. Amazon did not say if it would punish them for protesting.