Online retail giant Amazon has fired a security firm amid reports that foreign workers hired in Germany had been harassed and intimidated by guards with alleged neo-Nazi links.
She added Amazon has a "zero-tolerance" approach to "discrimination and intimidation and expects the same of other companies it works with".
It follows the screening of a documentary last week by German broadcaster ARD.
The programme had interviews with seasonal agency staff who claimed they had been mistreated by employees of the security firm, whose initials spell out the surname of Adolf Hitler's deputy Rudolph Hess.
It showed how workers, mainly at a warehouse in Bad Hersfeld and from countries including Spain, were subjected to constant surveillance by the guards in black uniforms with shaved heads.
One woman from Spain claimed she was threatened by security staff and after complaining about their behaviour her contract was terminated the following day without any explanation.
Two guards in the film were shown wearing Thor Steinar jackets - a clothing brand closely associated with far-right politics in Germany.
The documentary claimed Amazon paid seasonal workers at its German packing and distribution centres less than advertised and that their belongings were regularly searched in the temporary housing they were allocated.
It was also alleged foreign staff were initially promised direct jobs with Amazon. However, when they arrived in Germany they were assigned to an agency and given contracts for temporary placements which they could not understand because they were in German.
German services union Verdi has long accused Amazon of paying its temporary workers unfair wages and going overboard on surveillance.
The US company, which has about 7,700 people on staff in Germany and hires additional temporary workers at peak times to work at its seven packing and distribution centres there, has come under mounting criticism since the documentary was aired.
It launched an immediate probe into the allegations and said it would not tolerate intimidation at its sites.
HESS also denied any wrongdoing. However, it confirmed its guards had carried out room searches.
"The accusation that our company harbours far-right views or supports them is false," it said in a statement.
On Sunday, Germany's employment minister Ursula von der Leyen called for a thorough probe into the claims. She warned any proof of wrongdoing could result in serious consequences for the temporary employment agency used by Amazon.
"There is a strong suspicion here, which is why we need to lay all the facts on the table," she said.
"If the investigation shows there is something to the accusations against the temporary placement agency then its licence is at risk."