German authorities say they have raided 62 properties and arrested seven people in an investigation of an alleged trafficking ring set up to bring Thai women and transsexuals to Germany to work as prostitutes.

Prosecutors in Frankfurt said raids were conducted across Germany on Wednesday. They said the chief suspects are a 59-year-old Thai national and her 62-year-old German partner, who are suspected of setting up the network.

Officials say the couple ran three brothels in Siegen where the Thais, who entered Germany on fraudulently obtained tourist visas, were initially put to work as prostitutes before being sent on to other towns. Their wages allegedly were largely retained by the suspects.

Prosecutors say they so far have evidence that 32 Thais were trafficked into Germany by the group.