A police operation spanning seven countries has identified 156 perpetrators and victims of drug-facilitated sexual assaults, authorities announced on Thursday.

The victims were almost exclusively women.

"Investigations have uncovered online networks where perpetrators objectify and dehumanize victims," said Europol, which coordinated much of the investigations.

"They use encrypted messaging services, forums and closed chat groups to exchange experiences, normalize abusive behavior, facilitate the illegal trade in prescription medications and narcotics and coordinate criminal acts," Europol said. "These communications reveal detailed planning, reinforcing harmful actions, and sharing of material. They show that these crimes are not isolated incidents but part of a broader pattern of organized and interconnected behavior."

Operation Medusa was led by Germany's Federal Criminal Police Office (BKA) and Britain's National Crime Agency, with coordination through Europol. Law enforcement from Brazil, Canada, France, Hungary, the Netherlands, Spain and the United States contributed to the team.