The number of suspected online child sex offenders in Cambridgeshire has more than doubled in three years, according to a BBC investigation.

In 2014 there were 81 compared to 192 in 2016.

There were a total of 428 offenders in three years in the county.

The NSPCC is calling for a specialist digital child abuse unit in every police force and says the problem must be tackled at every level.

An NSPCC spokesperson said: “Downloading and distributing child abuse images is an abhorrent crime.

“Each picture is a crime scene involving a young victim who has been abused and whose suffering is compounded every time that image is passed around online.

“The proliferation of these appalling images is a major – and growing – problem which needs industry, government and law enforcement to tackle in unison.

“The NSPCC wants to see a specialist digital child abuse unit in every police force, trained to deal with sexual and other online offences against children.”

The Home Office said more resources than ever before were being used to target those involved in exploitation.

Under the Freedom of Information Act, the BBC found more than 4,000 suspected paedophiles had been identified across Northamptonshire, Cambridgeshire, Thames Valley, Hertfordshire, Norfolk, Bedfordshire and Suffolk in the last three years.

The Lucy Faithfull Foundation, which works to reduce the risk of children being sexually abused, said it currently deals with 700 to 800 calls nationally every month.

The foundation’s Donald Findlater said many paedophiles graduate from pornography to indecent images of children.

He said that three quarters of the men viewing those indecent images of children were previous to that viewing heavy adult pornography.

And he said that simply locking up paedophiles was not the answer

Online games and chat rooms are targeted, with offenders often posing as 13 or 14 year olds, he said, and added that rehabilitation provides an alternative solution to prison.

A Home Office spokesman said: “Child sexual abuse is abhorrent and we are determined to do all we can to bring perpetrators of these vile crimes to justice.

“Since 2010, we have increased support for victims of sexual abuse, invested in training and technology to improve law enforcement’s response to abuse both on and offline, and brought in a tougher inspection regime to ensure all front-line professions are meeting their child protection duties.

“Overall, in 2015, more than 2,800 individuals were prosecuted for indecent images of children offences, a 27 per cent increase on the previous year.”