Internet safety workers have warned more must be done to drive down demand for online child sex abuse images, as they revealed a record quantity of illegal content was found and blocked last year.

The annual report from the Internet Watch Foundation (IWF), to be published on Thursday, shows that the agency identified and took action on 105,000 images.

But it is an almost endless task, staff warned.

“It is like whack-a-mole,” said chief executive Susie Hargreaves.

“For 23 years we have been removing from the internet images and videos showing the sexual abuse of children.

“Despite us removing more and more images than ever before, it’s clear that this problem is far from being solved.”

The IWF digitally “fingerprints” images of child abuse it finds online, enabling them to be removed more readily from other sites and archives.

While only a tiny fraction of the 350,000 images it has so far listed and removed are hosted in the UK (0.04 per cent), there are estimated to be 100,000 people in the country looking at, or looking for, such images at any one time.

As a result, the foundation is calling for more action to tackle this demand by making people aware that there are real young people behind the content.

“With this continued demand for images of child rape, it’s a constant battle,” said Ms Hargreaves.

“That’s why we’re calling for all the partners to get together to run a long term, wellfunded prevention campaign.”

IWF is now planning too work with other partners and the UK Government to ensure people understand this is unacceptable and criminal, and can destroy the lives of the children involved for years to come.

Describing one harrowing case, workers said they first spotted Olivia, whose name has been changed, six years ago. IWF staff were horrified that she was being subjected to sexual abuse and the images posted online. She was three years old.

“She was a little girl with big green eyes and golden-brown hair. She was photographed and filmed in a domestic setting. Sadly, it may well have been her home and she was with someone she trusted,” one worker, part of a team of IWF internet content analysts, said.

“Olivia was in the hands of someone who should have looked after her, nurtured her. He betrayed her trust and in the most hideous way possible.”

The man almost certainly profited from his actions, she said, adding: “The suffering of children like Olivia is frequently a commercial crime.”