A senior police officer has warned vigilante "paedophile hunters" against taking the law into their own hands after a spate of apparent stings posted online.

Three Medway men have been arrested in the past week on suspicion of grooming underage girls after videos were posted on Facebook by amateur filmmakers calling themselves Unknown TV, claiming to have ensnared alleged sex offenders.

But Kent Police's paedophile investigation team is urging such groups not to put themselves in danger - or potentially jeopardise criminal cases - by trying to catch suspected perverts themselves.

Scroll down for video

It comes after Swanscombe paedophile Jeffrey Lewis was lured into a trap by campaigner Shane Brannigan, leading to his conviction.

Video: Swanscombe paedophile exposed by campaigners.

Lewis believed he was meeting a schoolgirl at London Bridge station for sex, but was instead met by Mr Brannigan who filmed the confrontation and posted it online.

"I would discourage people from taking the law into their own hands to avoid them being put in any possible danger" - DI Chitman

The 56-year-old pervert was arrested, and in September, jailed for four years after admitting arranging or facilitating the commission of a child sex offence.

Despite the success of this case, police are keen to encourage such vigilante groups to leave it to the professionals.

Detective Inspector Rob Chitham said: "I would like to reassure the public that we proactively target this type of offence and work hard to gather evidence in a lawful manner and that will stand up in court.

"I would discourage people from taking the law into their own hands to avoid them being put in any possible danger.

"Revealing the identity of suspected paedophiles, often on the basis of little information, often leads to suspects being threatened.

"This can divert significant police resources into protecting suspects, which would be better invested in investigating and, where there is evidence, prosecuting them."

A 47-year-old man from Gillingham was arrested on Saturday, and a 26-year-old man from Chatham was arrested the following day; both of whom were bailed until June 20 next year pending further enquiries.

Those arrests followed another on Thursday, of a 28-year-old man - also on suspicion of grooming - who was bailed until June 17, 2016.

DI Chitman encourages anyone with information about online grooming to call police on 101 - or 999 if a child is thought to be at immediate risk of harm - or Crimestoppers anonymously on 0800 555 111.