Scotland Yard’s online child sexual abuse and exploitation team received 2,514 referrals in 2018, up from 1,050 the year before – a 139 per cent increase.

Detective Inspector Tony Oakes said: “Although a referral may only show a single incident of abuse, investigators are trained to recognise and expose the fullest extent of offending. A typical search of a suspect’s address may result in the seizure of a significant number of devices for examination, including laptops, mobile phones and USB sticks. This process often shows the presence of tens of thousands of indecent images of children.”

Officers urged parents to remain vigilant to what their children may posting online and who they are talking to, after a rise in “self-generated” videos and photos being shared by paedophiles.

“What may start as a harmless conversation on a social media site, could well turn into online grooming where the child is asked to send explicit pictures of themselves,” Det Insp Oakes warned. “This image could then be shared amongst groomers until it is brought to our attention.”

In January, Scotland Yard received 317 referrals over possible online child sex abuse in London, including 212 from technology firms.

If the rate of reports continues for the rest of 2019, the year will finish with more than 3,800 referrals.

The number of child sex abuse image offences being recorded by police rose by almost a quarter to 22,700 in 2017-18.

The offences included taking, distributing and possessing indecent images of children and each one can involve hundreds of photos and videos.

Officials said the rise in recorded crimes does not necessarily reflect a higher prevalence of sexual abuse images and could be partly explained by better reporting by web companies, police recording, more proactive investigations and greater awareness.

The NSPCC said every image viewed “represents a real child who has been groomed and abused to supply the demand of this appalling trade”.

Police are increasingly concerned about the rise of “peer-on-peer” image sharing between minors, and some senior officers have called for “alternatives” to prosecution to ease strain on the criminal justice system.