Facebook has been accused of choosing to shield paedophiles for profit by ignoring police warnings that its plans to toughen encryption will make the platform a safe haven for abusers.

The warning came as one of the UK’s worst child abusers, David Wilson, was jailed for 25 years at Ipswich crown court after being convicted of 96 child sexual abuse charges, with more suspected.

Wilson, 36, from King’s Lynn in Norfolk, trawled social media platforms, predominantly Facebook, for victims, and was branded “sadistic” by the sentencing judge.

Wilson posed online as a girl, targeting boys so they would send images of themselves. His victims were as young as four, and some were so traumatised they wanted to kill themselves. Wilson’s response to one such traumatised child was to say “bye”.

As the grooming turned into abuse, some were threatened with blackmail if they did not do what Wilson demanded. Some were so terrified they abused and recorded their attacks on younger children.

Wilson mainly used Facebook and the company’s safety systems spotted suspicious activity and reported it to law enforcement.

Senior police chiefs say that chance to spot similar highly dangerous offenders online would be lost if the tech company switches its messaging services popular with children to end-to-end encryption.

Child sexual abuse is a largely hidden reality of modern Britain, police say, and they are overwhelmed. They say Facebook’s plans for encryption are so damaging, police are overtly using the Wilson case to drum up public support to stop it.

Rob Jones of the National Crime Agency, which caught Wilson, said he would have got away with his offending if end-to-end encryption had been in place, adding: “They [Facebook] appear to be putting the pursuit of profit above the safety of people, especially children on their platform.”

Jones said: “There isn’t a door I can put in that would deal with Facebook and if there was we wouldn’t hesitate.”

Facebook made 15.8m global referrals about child sexual abuse material in 2019 and Jones said it was crucial law enforcement worked with them.

Jones added: “Facebook’s plans are a disaster for child safety and law enforcement and mean the very many other David Wilsons out there will not be caught. Their plans will create a haven for child sex offenders to congregate to target children.”

Facebook is concerned its commercial rivals have end-to-end encryption, which it believes users want. It vows to continue helping police, and in a statement said: “We will continue to work with law enforcement to combat criminal activity. End-to-end encryption is already the leading technology used by many services to keep people safe online and, when we roll it out on our other messaging services, we will build on our strong anti-abuse capabilities.”

Last November Wilson pleaded guilty at Ipswich crown court to 96 offences against 52 children. The National Crime Agency said 500 children had sent Wilson images over a period of four years, and 5,000 had been targeted.

Wilson used pay-as-you-go phones, and hid behind fake identities online. Detectives had to prove Wilson was the person connected to the phones and false identities. It took three years to bring the former roofer to justice.

The majority of Wilson’s offending was committed while he was on bail as law enforcement desperately tried to get the evidence a court would accept to convict him.

Sentencing Wilson, judge Rupert Overbury said: “You carried out a lengthy and premeditated campaign of sadistic and manipulative abuse of young boys using social media. Any decent human being will be astonished at the level of depravity involved.”

One victim said: “At 12 years of age I was abused, blackmailed, made to feel suicidal. That’s something that no kid should have to go through.”

Tony Cook, from the National Crime Agency, said: “He groomed, bullied and blackmailed young boys into sending him indecent images and in some instances performing horrific abuse on themselves and others. Despite knowing their utter anguish and despair, he ignored their pleas for him to stop. He retained indecent material and threatened to share it among victims’ friends so he could maintain control of them.”

The home secretary, Priti Patel, said: “ It is vital that Facebook do not press ahead without amending their current end-to-end-encryption plans, otherwise sick criminals like David Wilson could still be abusing children with impunity.”