Vigilante groups seeking to expose paedophiles should stop taking the law into their own hands, Kent Police has said.
The force said paedophile hunter activities can hinder investigations and lead to offenders walking free.
Det Ch Supt Tom Richards of Kent Police said it also diverts resources away from cases involving real children.
Kent group The Hunted One said: "Police should concern themselves more with tackling paedophiles than us."
But Mr Richards said: "There have been zero cases in Kent where a vigilante paedophile hunter group has identified an individual who has at that stage presented a real risk to a real child.
"In the last two financial years, vigilante groups in Kent have contributed to 20 individuals being arrested but my resources alone in the same period have arrested 299 people."
Professor Martin Gill, a criminologist working for Perpetuity Research, said: "There is nothing worse than a police investigation to get to its crescendo and then be undermined by an often well-intentioned but disastrous intervention."
The Hunted One claims to have caught 57 people, leading to 27 convictions.
In October last year, Mark McKenna from Northfleet was jailed for five years after he was snared by The Hunted One.
The 38 year-old thought he was meeting an 11-year-old girl for sex at Bluewater Shopping Centre in Kent.
But instead of talking to a vulnerable child online, he was speaking to the group of concerned parents.
Ben Bleach of The Hunted One said he could not understand why "a child has to be raped" before action is taken.