Social worker Estelle Thain told ITV News that she became increasingly concerned about one of the Peterborough victims when she became "too frightened" to speak about her experiences.
"It got to the point where we had to place her in foster care to move her away from Peterborough," she said, "which was where she was putting herself at risk."
"She had been moved a couple of months to foster placement, which was a long way from Peterborough, before she got to a point where she got comfortable to disclose some of the things that had been happening to her."
"She was 12 or 13 at the time," she added.
More top news
Freezing temperatures, a biting wind and risk of snow into next week
Austerity and Brexit are dividing Britons and causing a "schism" in society, the Archbishop of Canterbury has warned.
A taxi driver has been suspended after inspectors found he was using a Costa Coffee lid as a fuel cap.