At least 300,000 people in the UK pose a sexual threat to children as paedophiles look to exploit the coronavirus lockdown, the National Crime Agency (NCA) has warned.

Investigators have identified offenders discussing opportunities to abuse children during the Covid-19 crisis in chats online.

And police are warning of a spike in abuse with schools closed and youngsters spending more time on the internet.

Chief Constable Simon Bailey, the National Police Chiefs’ Council (NPCC) lead for child protection said: “It is sickening to think that some criminals are looking to exploit the coronavirus crisis to cause harm online.

“Despite the issues that the pandemic will cause for law enforcement, child protection is still a priority and we remain totally committed to keeping our young people safe.”

It comes after the NSPCC warned that children stuck at home using the internet during lockdown creates a “perfect storm” for offenders to abuse online.

The NCA estimates a minimum of 300,000 people in the UK pose a risk of committing physical or online child abuse, while investigators were able to find child sexual abuse material on the open web in just three clicks.

The figure, published in the agency’s latest national strategic assessment on Friday, includes around 250,000 UK-based user accounts on the worst child abuse websites on the dark web – up from around 140,000 last year.

The NCA said some 94,342 UK residents contacted the Lucy Faithfull Foundation child protection charity to report themselves or someone close to them who was sexually attracted to children in 2019 – up from 43,000 the previous year.

Susie Hargreaves, chief executive of the Internet Watch Foundation (IWF), a UK charity involved in finding and removing child sex abuse images and videos from the internet, said: “This is a terrifying escalation of the threat to our children.

“These numbers are unlike anything before. It’s a genuine threat to our children right now.”

She added: “It is horrifying to think sexual predators are viewing the coronavirus crisis as an opportunity to exploit a captive audience of children, who are spending more time at home on their devices.”

The intelligence pre-dates the coronavirus outbreak but the NCA and NSPCC are urging children, parents and carers to ensure they know how to stay safe on the web as they face an increased threat from offenders online.

Rob Jones, NCA director of threat leadership, said: “Child sexual abuse remains a priority threat for the agency at this difficult time.

“Though we are working around the virus like everyone else, we are continuing to pursue high-risk online offenders to ensure they are arrested and children are safeguarded.

“The internet has undeniable benefits to society.

“But it’s also enabled a section of society to commit increasingly horrific crimes against children through grooming, live-streaming and distribution of indecent images.

“Preventing offences occurring is always crucial and now more so than ever when there is masses of online traffic and a possible elevated threat to children.”

The NCA said it has launched a #OnlineSafetyAtHome campaign and will issue information and educational tools through its Thinkuknow website and social media channels, with specific Covid-19 content released through the Parent Info site.

Donald Findlater, director of the Stop It Now! helpline, which is run by the Lucy Faithfull Foundation, said: “In this time of serious worries due to coronavirus, it’s important that every parent and grandparent is aware of the support available to help them keep children safe.

“So as families try to keep education going, these engaging online safety resources are a great idea.

“With normal life so different for all of us, parents are more than ever at the forefront of keeping their children safe online and offline, and knowing where to get help and support is vital.”