There could be thousands more paedophiles in the UK than previously estimated, the head of the National Crime Agency has said.
Speaking at the launch of the NCA's annual national assessment of serious and organised crime, Lynne Owens said there could be 140,000 people with a sexual interest in children in Britain who access images online.
Previous estimates made public in late 2017 put the figure at around 20,000, and more recently at 80,000, but investigations into the dark web have unearthed thousands more accounts accessing the worst kind of images.
The NCA has found 2.88 million users registered on child abuse networks on the dark web, at least 5% of which - around 140,000 - are UK-based. It is not known whether each of these is one individual, or whether users have multiple accounts.
Ms Owens said: "What we have been able to see in history is activity on the open web. Now that we have identified these 2.88 million dark web accounts, we see a very sinister pattern of offending."
Investigators do not have the resources to go through every account.
Director general Ms Owens warned that law enforcement needs a funding boost of £2.7 billion over the next three years to keep up with changes in serious and organised crime.
She wants the agency to receive an extra £650 million per year - which would see its budget, predicted to be around £475 million for 2019/20, more than double.
The estimated number of offenders involved in serious and organised crime, thought to be around 181,000, is more than twice the strength of the British Army.
Ms Owens said: "Serious and organised crime (SOC) in the UK is chronic and corrosive, its scale is truly staggering.
"It kills more people every year than terrorism, war and natural disasters combined.
"SOC affects more UK citizens more frequently than any other national security threat. And it costs the UK at least £37 billion a year, equivalent to nearly £2,000 per family.
"We need significant further investment to keep pace with the growing scale and complexity.
"Enhancing our capabilities is critical to our national security. If we don't, the whole of UK law enforcement, and therefore the public, will feel the consequences."
As well as dealing with growing demand, the NCA would aim to boost digital forensics, covert surveillance and financial investigations with additional funding.
Ms Owens added: "Some will say we cannot afford to provide more investment, but I say we cannot afford not to.
"The organised criminals of today are indiscriminate, they care less about what types of crime they're involved in, as long as it makes them a profit.
"These groups are preying on the most vulnerable in society, including young children and the elderly, those most unable to protect themselves.
"The choice is stark. Failing to invest will result in the gradual erosion of our capabilities and our ability to protect the public."
The NCA's annual National Strategic Assessment (NSA) found that the number of county lines gangs has surged from 720 to more than 2,000 in around a year.
The drug-dealing networks operate lucrative phone lines, delivering illegal substances from urban bases out to more rural areas.
They are known for forcing young and vulnerable people into crime. The NCA said that in some areas there are now crime gangs nearly solely made up of children and young people.
The 2019 NSA also found:
- Traditional organised crime gangs have broken down into networks of younger offenders who use the latest technology, as well as extreme violence, to carry out a range of crimes
- Professionals such as accountants and solicitors are "increasingly facilitating crimes with their expertise"
- The use of the dark web and encryption to avoid detection have grown significantly, with an increase in cryptocurrencies being used to launder money
As well as organised crime, the NSA looked at child abuse, modern slavery and fraud. It found that:
- There are nearly 2.9 million accounts registered on the worst child sexual abuse sites on the dark web worldwide, around 5% of which are from the UK
- The number of referrals to the NCA from internet firms of suspected online child sexual abuse and exploitation have increased seven-fold since 2013.
- Referrals of potential victims of modern slavery have increased by more than 80% since 2016.
- There were 3.6 million incidents of fraud reported in England and Wales in 2018, and financial losses from fraud rose by 32% between April and September.