Emergency services were called to the site at 6.25pm yesterday.
According to local newspaper The Herald, two off-duty retained firefighters that worked at the mill were immediately available to extricate the man from the machine and administer first aid. The man was then flown to Derriford Hospital by Devon Air Ambulance but later died of his injuries.
The Herald added that the firefighters had since received counselling.
The Health and Safety Executive has been informed.
Unite assistant general secretary Tony Burke said the union, which represented the dead man, would be involved in an investigation into the "horrific accident".
He said: "This is another massive blow to the papermaking industry and Unite will be giving consideration to convening a meeting within the papermaking industry on the whole question of health and safety.
"Our condolences will be sent to our member's family and they will of course receive the full support of our Union."
Unite officials are currently on site and the union will issue a joint statement with the Health and Safety Executive and the company when more details are known.
A spokesman for Sequana, Arjowiggins' French parent, said that Arjowiggins will not comment at this stage.