FRANKFURT -- German authorities searched 62 brothels, offices and homes in several federal states and arrested seven people on Wednesday in a crackdown on suspected human trafficking in connection with a Thai prostitution ring, prosecutors said.

Police said on Twitter that the raids, which involved more than 1,500 officers, prosecutors and tax officials, represented the biggest mass search in the history of the federal force.

The investigation has turned up 56 people, aged 26 to 66, who are suspected of crimes related to human trafficking, forced prostitution, pimping, withholding of wages and tax evasion, the Frankfurt general prosecutor’s office said in a statement.

Prosecutors suspect that a number of people, led by a 59-year-old Thai woman and her 62-year-old German partner, brought women and transsexuals from Thailand to Germany on tourist visas and forced them into prostitution, it said.

The woman is suspected of keeping money that the prostitutes earned, supposedly to cover the cost of bringing them to Germany as well as for room and board at several brothels in the western town of Siegen, and of eventually passing them on to brothels elsewhere.

“The investigation has so far identified a total of 32 women and transsexuals who were smuggled into Germany by the suspects and who allegedly worked in the brothels as prostitutes,” the prosecutor’s office said.