Babies and toddlers are suffering the worst forms of child sex abuse online, leading campaigners have warned.
New statistics show that over the past three years, thousands of webpages showing abuse of children aged zero to two were more likely to feature category A images - involving penetrative sexual activity, sexual activity with an animal or sadism.
The data has been compiled by the Internet Watch Foundation (IWF), whose chief executive Susie Hargreaves called the research "shocking".
The Home Office said it was leading global efforts to tackle the sexual exploitation of children online, adding there was more technology companies could do.
IWF research found that from January 2014 to September 2017, 63% of child sexual abuse material showing children aged zero to two was category A.
For three to six-year-olds, the figure was 57% and for seven to 10-year-olds, 36% of images were category A.
For the 11 to 13 age group the figure was 20%, for 14 to 16 they amounted to 16% and for 16 to 17-year-olds it was 7%.
"These shocking statistics speak for themselves - the worst abuse is suffered by the youngest," Ms Hargreaves said.
"As everyone knows, babies are utterly defenceless.
"That means every day our analysts are working to stop these horrific images of young babies and toddlers being raped and tortured from being shared on the internet.
"We know these statistics will horrify and upset people, but it's important that people understand why we need to keep doing what we do."
The Cambridge-based charity monitors online child sexual abuse images and works internationally with internet companies to get them removed.
Since it was launched in 1996 the amount of child sexual abuse material hosted in the UK has fallen from 18% to 0.1%, Ms Hargreaves said.
She added: "Despite this, we still find one of these images or videos every nine minutes, which is why we need a global effort to see this material removed once and for all."
Category B images, or those involving non-penetrative sexual activity, are more consistent across all age groups, ranging from 17% to 30% of the overall images seen.
Images of 14 to 15-year-olds were most likely to be category C - those not falling within categories A or B.
Overall the IWF saw:
- 5,802 webpages showing images of zero to two-year-olds;
- 32,462 webpages with images of three to six-year-olds;
- 99,703 webpages with images of seven to 10s;
- 75,077 for 11 to 13;
- 5,023 for 14 to 15 and
- 3,518 for 16 to 17-year-olds.
One webpage can contain between one and thousands of images.
A Home Office spokeswoman said the sexual exploitation of children online "is an appalling crime which we are committed to stamping out".
She pointed to initiatives such as new specialist teams at the National Crime Agency, adding: "Through the WePROTECT Global Alliance, we have already got six major technology companies to agree to scour their sites for the digital fingerprints of over 50,000 Category A images identified from the UK's Child Abuse Image Database.
"But there is more for these companies to do, particularly around Category B images of an adult abusing a child, which they are not taking enough action to remove.
"We're trying to help them which is why earlier this month the Home Secretary announced investment in Project Arachnid, which makes use of software to identify indecent images on the internet rapidly so that technology companies can more easily take them down and prevent the ongoing victimisation of the children who have been exploited to produce them."
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