Police are working to establish if 22 suspected child sexual exploitation cases in Northern Ireland are linked to potential organised abuse activities.
Officers have stressed they have found no evidence of a so-called "sex ring" operating in the region, but they have identified some connections with the cases.
A majority of the children involved lived in residential care homes at the time of incidents, but the allegations relate to periods when they were not in the facilities, such as on nights out when they failed to return.
Both boys and girls have allegedly been targeted.
Some of the alleged crimes date back to early 2011 and all have been previously investigated separately.
But after a review of the cases, the Police Service of Northern Ireland (PSNI) has announced an overarching investigation drawing all the cases together.
A senior police detective today revealed that up to fifty suspects have been identified to date and arrests have been made in each case. A number of individuals have been charged, though some with non-sexual offences such as drug crimes.
PSNI Detective Superintendent Sean Wright said: "We haven't identified a sex ring, but we are looking for it."
The officer added: "We have looked to see if there are links and connections across. We can see, for example, that many of the children know each other, we can see that some of the suspects know each other.
"What we are trying to now understand is what or how significant those links are, how organised this may or may not be, and through those investigations to try and understand what degree of organisation is in place by these perpetrators to groom and exploit young people.
"We haven't uncovered any sex ring, I want to be absolutely clear about that, we have no evidence of it, but we are looking."
Social workers and a representative from childrens' charity Barnardos are working alongside the team of PSNI detectives handling the cases.
Mr Wright said the investigation was "complicated", highlighting that the "vast majority" of the alleged victims did not view themselves as victims.
He said: "Where a victim doesn't see themselves as a victim, they tend not to co-operate with the police, social services or any of the other statutory services who want to bring these perpetrators to justice.
"Victims will tell us that the person who had sex with them, or took them to a party and gave them drink and drugs and encouraged them to perform sexual acts on their friends, is actually their boyfriend and they love them very dearly.
"So there is no way on this earth that they are going to give us a statement to put their boyfriend in jail.
"Please do not underestimate the complexity of this."
Of the 22 alleged victims, some were not residing within the care system at the time of the suspected offences.
Mr Wright said the PSNI had been working with colleagues from England, such as those involved in the recent major investigation into organised child abuse in Rochdale, to help inform their work.