Germany is demanding explanations from the online retail giant Amazon after a TV documentary showed seasonal workers being harassed by security guards.
A TV documentary by state broadcaster ARD said employees' rooms were searched, they were frisked at breakfast and constantly watched.
Employment Minister Ursula von der Leyen said some employment agencies could lose their operating licences.
In a statement, Amazon said it would follow up complaints.
"The suspicion weighs heavily; therefore all facts must be put on the table as quickly as possible," Mrs von der Leyen told the Welt am Sonntag newspaper.
"If the special investigation finds that there is some substance to the complaints against the employment agencies, then their licences are in question."
The film showed the living and working conditions of agency workers brought in to help with the Christmas rush, principally at an Amazon warehouse in Bad Hersfeld, in the state of Hesse.
It showed staff living quarters in cramped holiday accommodation a long way from the Amazon warehouse, which could only be reached by an unreliable bus service.