Police chiefs have accused vigilante paedophile hunters of exceeding the law, despite using their evidence to prosecute suspects in more than half of all cases.

Senior officers have criticised the online groups – who pose as youngsters in order to smoke out predatory paedophiles – claiming some are guilty of offences such as blackmail, extortion and violence.

But despite these reservations the most recent figures reveal the extent to which police forces rely on evidence gathered by such gangs to catch offenders.

According to data obtained by the BBC under the Freedom of Information Act, 403 people were prosecuted in 2018 for the offence of attempting to meet a child following sexual grooming.

More than 250 of those were charged following evidence gathered by paedophile hunting groups and in some force areas it accounted for 100 per cent of all cases.

An analysis of crime statistics shows how convictions for grooming offences have rocketed more than five fold since 2013, suggesting the emergence of paedophile hunter groups is helping to bring more dangerous predators to justice. 

In 2013 there were just 68 people convicted of grooming offences, but by 2018 that figure had risen to 359.