Minister for Justice of Northern Ireland Naomi Long expressed concern that not all sleep by Alexander McCartney victims can be identified.

The online predator who drove one of his own victims in the US to take her own life, was sentenced to at least 20 years in prison at Belfast Crown Court on Friday.

McCartney, 26, who admitted 185 charges involving 70 children, posed as a teenager to befriend young women on Snapchat before blackmailing and luring victims around the world.

He is believed to be one of the most prolific in the world online criminals.

While he was jailed on charges involving 70 victims, the number of children he abused is believed to be around 3,500.

Ms Long urged anyone who had been abused by McCartney or anyone else to come forward.

“The sad part of all of this is that some of those victims may never be identified, and I think that’s really upsetting for the (police) officers, as it is for the rest of us, but at least the perpetrator he has been identified and will serve a considerable period of time in prison for what he has done,” she told BBC Radio Ulster’s Good Morning Ulster programme.

“There were quite exhaustive inquiries that were undertaken at the time during the investigation to try and identify who those children were and for some, that was possible across the globe. For others, they were not traceable and I don’t think it will be easy, although there may be some who, reading about the sentence in this case, may come forward.

“I would certainly encourage anyone who has been abused in this way by McCartney or others to come forward to their local police to say what is happening. Many of these children were terrified of what would happen to them if they said what they had done because they felt guilty about their behaviour.

“Nobody should feel scared that they have been put in this situation. They are the victim and if someone is being black mailed like this I would really encourage them to get help, talk to someone, you will be treated as a victim not a criminal and get the support you need. “

Ms Long also paid tribute to the police officers who carried out the investigation and the Crown Prosecution Service.

“Those officers spent hours watching footage that no human being should ever see to make sure this case could be brought to trial,” she said.

“It was a complicated case, new parts of the law were tested in terms of online behavior but I think it’s a credit to them that it came down to this.”