A new policy at Amazon, which can result in punishment or termination for employees who publicly criticize the company's stance on climate change, has prompted more than 350 employees to speak out in protest.

The employees claim the company is trying to silence their activities, which includes urging Amazon to phase out fossil fuel use, and to stop making its cloud computing services available to the oil and gas industry. "It's our moral responsibility to speak up, and the changes to the communications policy are censoring us from exercising that responsibility," Sarah Tracy, a Software Development Engineer at Amazon, said in a statement on Sunday.

To protest the policy, the employees published a blog post with their names and titles attached, demanding Amazon act faster to eliminate the company's carbon footprint when the e-commerce giant is routinely shipping packages to customers across the globe. On Monday, they also began circulating a video, which shows more than a dozen employees holding up signs that say "We will not be silenced #AmznSpeakOut."

"Corporations cannot own conversations that affect our very existence," they says in the video.

Over the past year, employees have organized to publish an open letter containing more than 8,700 signatures from staffers, and staged a walkout at company offices to pressure Amazon to phase out fossil fuels. The protests grabbed headlines and support from Democratic presidential candidates at a time when workers across the tech industry are increasingly resorting to public activism.

In response, Amazon has committed to reaching net zero carbon emissions by 2040, which will involve using a new fleet of electric vehicles to make customer deliveries. However, the protesting employees want the e-commerce giant to accelerate the timetable to 2030 and to also cut off the oil and gas industry from using the company's cloud computing technologies.

In a statement, Amazon said the company is "passionate" about preventing climate change. "We plan to be using 100 percent renewable energy by 2030, and we have thousands of people working on sustainability initiatives across the company," the company added.

Nevertheless, Amazon is holding the line on forbidding any unsanctioned public comments from employees attacking the company. "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," the statement added.

Amazon went on to say employees are free to provide feedback on its policies internally, whether it be during company meetings, joining in-house interest groups, or reaching out to company CEO Jeff Bezos himself via email. Amazon also stressed the communications policy was nothing new and is likely similar to how other large companies operate. However, the protesting employees claim Amazon has been dragging its feet on addressing climate change.

"I and others tried for years to raise issues via internal channels but it didn't work. I used to think that Amazon's leaders had a plan to address the company's climate impact and I learned that they didn't," wrote former Amazon employee Eliza Yu-An Pan, who was among those who joined in the protest.

The employees say Amazon introduced the new communications policy after two staffers provided a quote to The Washington Post in October that was critical of the e-commerce giant's ongoing effort to supply technology to help fossil fuel companies extract new oil reserves more quickly. An Amazon lawyer reportedly warned them that speaking out again could result in formal corrective action, including termination of their jobs.

So far, the company has not said whether it plans on punishing the protesting employees. Last year, Amazon reported having 647,500 full-time and part-time employees on staff.