Hundreds of Amazon employees have openly criticized the environmental position of the online retail giant in violation of the company’s communications policy.

More than 300 employees have signed a Medium blog post by Amazon Employees for Climate Justice (AECJ) which urges the company to go further in its plan to tackle climate change, which was announced to the public in September.

The group members publicly criticized the company, but some were warned they could be fired. “The protest is the largest action by employees since Amazon began threatening to fire workers for speaking out about Amazon’s role in the climate crisis,” the AECJ said, according to Novinite.

“As Amazon employees, we are responsible not only for the success of the company, but also for its impact. Our moral responsibility is to publicize and changes in communications policy prevent us from exercising that responsibility,” said Sarah Tracy, a development engineer of the software at Amazon.

Amazon has nearly 650,000 full-time employees at the end of 2018, according to the company’s annual report.