An investigation has been launched into allegations of sexual abuse against children in care in Essex during the 1980s and 1990s.
Essex Police said the possible crimes had been raised during a meeting between chief constable Stephen Kavanagh, police and crime commissioner Nick Alston and people who worked with children in the county at the time.
Serious concerns were raised about alleged sexual offences committed against children, particularly boys in local authority and foster care, the force added.
Further concerns were raised about the protection and support offered to young people who may have been victims of abuse.
Mr Kavanagh said: "At present we have allegations but no victims, suspects or locations.
"But whether alleged abuse, especially organised and institutionalised, happened yesterday or 30 years ago, it's our duty to review it without fear or favour."
Former district psychologist Robin Jamieson, a former clinician manager of the Suffolk Child Sexual Abuse Treatment Service, Jenny Grinsted and youth worker and probation officer Rob West were present at the meeting last month, a statement said.
Concerns were raised that, although a number of allegations had previously been investigated and prosecuted and two convictions were secured, those investigations may not have been "sufficiently thorough".
Mr Alston said: "The abuse of a child, whether in the care of their parents or the state, is an abhorrent crime.
"Professionals who worked in Essex during the 1980s and 1990s have raised serious concerns with both chief constable Kavanagh and me, and it is right that Essex Police examines these allegations meticulously and seeks out any new evidence.
"For an adult to come forward and report abuse suffered as a child takes real courage. I would say to anyone in this situation: please come forward and trust us.
"You can speak to Essex Police directly, or to a specialist organisation which can provide support and help."
Survivors of sexual abuse in Essex in this period are being urged to contact the force child abuse investigation teams on 101.
Those involved can also contact the Independent Inquiry into Child Sexual Abuse through the NSPCC information line on 0808 800 5000 or by visiting www.iicsa.org.uk.