Officers have spoken to more than 200 people to "identify victims and witnesses", Surrey Police said.
The investigation centres around a home in Woking, known as Kinton Approved School and the Oaks Centre, Mayford, from the 1970s to the early 2000s.
Police said 17 people have been arrested or interviewed under caution.
The number of children involved is unknown, but a police spokesman said the investigation was "large and complex".
The home, run by Surrey County Council, was closed in the early 1990s.
Keith Hammerton, 69, of Battersea was jailed for six years on November 1 for sexual offences he committed against boys while employed as a housemaster at Kinton approved school in Mayford in the 1970s.
If you, or a loved one, have been affected by historic sexual abuse and wish to discuss whether you have a viable claim, please do not hesitate to contact our team of experienced lawyers who will be happy to speak to you in the strictest of confidence.
Below is a selection of organisations/instutions/bodies we are frequently instructed to pursue.
Private schools, boarding schools, local authority schools, closed schools, hospital schools.
The Scouts Association, St Johns Ambulance, MIND, the Children’s Society, Barnados.
- Football trainers, judo teachers, dance instructors, swimming instructors, holiday activity centres, nurseries, youth clubs.
Local Authorities/Ministry of Defence
- County Councils, Borough Councils, City Councils, ILEA, cadets, navy/ army (forces).
National Health Service Trusts/Commissioning Boards/GPs
- Hospitals, Disability care centres, children’s care providers.
- Convicted perpetrators, acquitted perpetrators.
- Respite care, full time children’s home, part-time children’s homes.
- Roman Catholic Church, United Synagogue, Sisters of Nazareth, Jehovah’s Witnesses, Christian Brothers Order.
- Permanent carers, temporary carers
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