Amazon in Swansea employs 1,200 permanent staff and hires more than 2,000 temporary staff at Christmas.
A former worker at Amazon's Swansea warehouse has claimed staff are treated "like robots" and routinely sacked for not meeting "unrealistic targets". The worker, who did not want to be identified, said it was an "intimidating" place to work.
"Things like timed breaks, constantly monitoring you. Not being able to have the freedom to go to the toilet without someone coming and being like, 'right, you've been five minutes away from your task now what have you being doing?'. You are essentially a robot trying to get everything 100% perfect, and if you don't meet those standards then you know about it. I'd say they treat you like a number and they treat you like robots, and after a while, because of the brain-numbing work, you become a little bit of a robot as well...ou were very aware that you were part of an expendable workforce."
It comes as a union demanded talks with the online giant over safety and working conditions there.
Since 2015/16, there have been 84 serious incidents reported to the Health and Safety Executive (HSE) - the second highest of Amazon's UK centres.
The GMB Union, which made the claim about the number of health and safety incidents at the site, said the figures spoke for themselves.
Regional organiser Jeff Beck said: "People are under so much pressure there they've been dehumanised, they've been turned into robots, and that's when the accidents are occurring."