Online retailer Amazon is investigating reports its staff were subjected to intimidation by security guards with neo-Nazi connections.

A documentary shown on Germany's ARD channel made allegations about the treatment of some 5,000 temporary staff hired by temp agencies on Amazon's behalf at packing and distribution centres in the country.

It claimed workers are forced to live in cramped houses, often work for 15 consecutive days and earn considerably less money than they were promised before leaving their home countries.

One told the film-makers: "It's like being in a machine and we are just a small part in this machine."

The footage also reveals the presence of guards wearing black uniforms, boots and military-style haircuts, who are apparently employed to keep order at the properties where the foreign workers lived.

The guards wear black uniforms emblazoned with HESS Security - which ARD suggests alludes to Adolf Hitler's deputy Rudolph Hess.

SEE ALSO: Fidel Castro Hired Former Nazi Waffen SS Officers To Train Cuban Troops

Several guards are also revealed to be wearing Thor Steinar clothing - a Berlin-based designer brand synonymous with the far-right in Germany, The Independent points out.

It adds the label is banned by both the Bundesliga football association and the federal parliament owing to its neo-Nazi associations.

"Amazon tolerates no discrimination or intimidation," Amazon spokeswoman Ulrike Stoecker told The Associated Press in an email.

"Even though the security company wasn't hired by Amazon we are of course examining the allegations (...) and will take appropriate measures immediately."

German daily newspaper Sueddeutsche Zeitung is referring to the matter as a "shitstorm".

According to hr-online.de, the German Trade Union Federation (DGB) has demanded the intervention of the state government.