Police shut down a party arranged on social media by people looking to sexually exploit children, a report has revealed.
Officers from Staffordshire Police took home 40 schoolgirls aged 14 and 15 after stopping them from attending the party on February 5 in the Bucknall area of Stoke-on-Trent.
The "majority of the people" who turned up at the party did not enter the house, police said.
Details of the party emerged in the force's response to a report by Her Majesty's Inspectorate of Constabulary (HMIC) into the force's effectiveness.
Pointing to how the force investigates "new types of crime", Chief Constable Jane Sawyers said: "An operation stopped groups who were organising parties through social media to attract young females in North Staffordshire with the intention to carry out child sexual exploitation."
A spokeswoman for the force added: "The operation looked at the way that social media was being used to advertise house parties across Stoke-on-Trent.
"The police had been made aware of reports, through disclosures to teachers, care workers and occasionally parents that some sexual activity had taken place at some parties within the city.
"The response by the police and partners has been to look to identify when and where such parties are taking place with a view to ensuring they are being properly managed and young people attending them are safe.
"On the occasions where we felt it appropriate to disrupt or prevent parties from taking place, we have done so."