Some 1,330 customs officials, as well as state and federal police, collaborated to search 180 apartments and restaurants. The operation, headed by the Lower Saxony state prosecutor’s office in Hannover, is working on evidence that more than 1,000 “specialty cooks” have been brought to Germany in the last several years to work gruelling hours for meagre pay.

The raids were meant to gather evidence against three Hannover-based Chinese ringleaders, a statement from the state prosecutor said. The two men and one woman have been imprisoned on remand since March and are believed to have earned millions in euros by bringing the cooks to Germany and then faking their employment records while paying them well below the legal limit.

Among computer data and other evidence gathered, police collected assets that could be used to compensate the underpaid cooks for their damages.

The investigation focused on the Hannover region but also included the states of Hessen, Rhineland-Palatinate, and Saarland.