Northumbria Police have carried out further raids in Newcastle and Gateshead on several properties as they reacted to information about a series of sexual assaults.
As part of Operation Sanctuary, three more people were arrested yesterday, bringing the total to 16 men and two women, all on suspicion of conspiracy to rape.
The 15 people detained on Monday have been bailed.
Police said some of the victims were in care when the alleged offending took place and that their priority was to protect them and ensure their safety. Temporary assistant chief constable Gary Calvert said: "Our priorities remain to arrest those believed to be responsible and to offer support to safeguard those victims already identified, while encouraging anyone else who believes they may know or have been a victim themselves to talk to us."