Three Pakistani men are already under arrest after 18 women filed complaints alleging they had been improperly touched, fondled and groped during the festival in the city of Darmstadt.
Police have said the number of complainants could rise.
As in Cologne on New Year’s Eve, when asylum seeking men moved in hunting packs through the concourse of Cologne main railway station to rob and sexually attack hundreds of young women, the Darmstadt men are alleged to have moved in groups to prey.
All the complainants claimed they were “surrounded” by their tormentors before being “touched and fondled” improperly at the annual free Schlossgrabenfest music festival over the weekend.
The three arrested men are aged between 28 and 31 and are Pakistanis seeking asylum in Germany.
Media reports said that at least 15 more women are expected to come forward to file criminal complaints after they were allegedly groped at the festival on Sunday, where around 100,000 people were in the crowds over the four-day event.
Since Cologne there have been numerous reports of migrants sexually attacking German women, but many of them turned out not to be true.
But the Darmstadt victims all came forward independently to tell graphic tales of the alleged assaults which quickly led to the arrest of the men.
The Pakistanis will face deportation to their homeland if found guilty when brought before the courts.