Hanover - A Chinese people-trafficking gang is thought to have smuggled more than 1,000 compatriots into Germany over a period of years to work as Chinese chefs, criminal investigators in Hanover reported Monday.

Hanover state prosecutors said they were investigating on charges of people trafficking and exploitation, after 1,300 police and customs officers had uncovered evidence spanning four German states.

Raids were carried out at lunchtime in 180 Chinese restaurants and apartments, in the states of Lower Saxony, Bavaria, Baden-Wuerttemberg and North-Rhine Westphalia.

Back in March, police had arrested two Chinese men and a woman in Hanover. The trio had founded a firm to orchestrate their smuggling activities, according to criminal investigations.

The three Chinese held in custody, aged 46, 38 and 35, are thought to be the chief operators in the trafficking ring.

"They made sure all the forms were correct," said spokesman for Hanover state Office of Criminal Investigation, Frank Federau.

For a cost of 10,000 euros, Chinese emigrants were given a valid visa and work contract. Upon arrival in Germany, they were forced to surrender their passports.

"They stood in downright debt servitude," Federau said.

The immigrant Chinese were given jobs, and those who were not trained chefs were quickly brought up to speed, investigators found.

The chefs were made to work for 80 to 90 hours a week, at an hourly wage of 3 euros (4.26 dollars). Their lack of German language skills made it difficult for the immigrants to complain.

As for the people smugglers in Germany and their associates in China, the investigations revealed that they had pocketed "revenues in the millions," according to Federau. (dpa)