A 23-year-old man has been arrested in Co Down on suspicion of attempting to meet a child following sexual grooming.
A self-styled 'paedophile hunter' group claimed it supplied the information to police which led to the arrest in Banbridge on Saturday evening.
It was alleged the man had contacted a 15-year-old girl online and arranged to meet her.
In a tweet on Saturday evening, PSNI chief inspector Jon Burrows confirmed only that a man had been arrested.
"Officers from PSNI Armagh, Banbridge and Craigavon arrested a 23-year-old male in Banbridge this evening on suspicion of attempting to meet a child following sexual grooming," he said.
"The district are working with detectives in the Public Protection Unit to thoroughly investigate the allegations."
There are at least six known 'paedophile-hunter' groups active in Northern Ireland, but their tactics have drawn criticism from police and other bodies.
Last week, a senior PSNI officer said such groups had referred 77 possible cases to police since last June.
Usually, the groups use adult decoys pretending to be children in online chatrooms but on the latest occasion it is understood a girl reported communications to her parents, who then contacted the group Predator Catchers NI.
The mother of the 15-year-old girl, who asked to remain anonymous, said she was proud that her daughter had reported the communications to her.
"There is a lot of children out there who would be afraid to come forward," she said.
"Furthermore, the team that dealt with this case did so with the utmost professionalism at all times.
"I cannot thank the team enough for the work they do for the children of Northern Ireland and it’s because of the Predator Catchers NI team that parents are been made aware of what is really going in this country."
