At least 40 illegal workers were employed in building a new clinic in Göppingen.
During a routine check, the police discovered numerous violations of labor law, as they announced on Thursday.
Four companies are said to have paid their employees less than the minimum wage.
In addition, the officers picked up two wanted people on Wednesday and arrested one of the two on site.
Göppingen - The Alb Fils Kliniken declared that they had duly advertised and awarded the construction contracts for the new building of the “Klinik am Eichert”.
According to the contracts, it is the construction companies' duty to adhere to the legal requirements.
"That this was presumably not kept by some companies annoys us tremendously", explained the commercial director Wolfgang Schmidt.
dpa