A total of 87,000 web pages featuring images of child sexual abuse have been deleted over the past 15 years, according to a foundation which polices the internet.
But while the proportion of criminal pages hosted in the UK has dropped significantly, foreign-hosted websites remain a problem and images are becoming increasingly extreme.
The Internet Watch Foundation (IWF), based in Cambridge, is the UK's hotline for reporting criminal content online and is celebrating its 15th anniversary by highlighting the impact it has had after assessing 370,000 web pages and removing 87,000 containing criminal content.
Chief executive Susie Hargreaves said the foundation was proud of the work it had done so far but added that combating the continued threat remained a priority.
She added: "Although we've had tremendous success domestically, child sexual abuse content on the internet is a problem the IWF and the industry are eager to tackle wherever it is hosted.
"With the industry and partner hotlines' support we've been able to remove 87,000 web pages containing some of the worst content depicting the rape and sexual torture of young children and babies."
Since the IWF was launched, the volume of UK-hosted child sexual abuse content has reduced from 18% in 1997 to less than 1% since 2003 but there is still a problem with child sexual abuse content hosted around the world.
During its history 45% of worldwide web pages assessed and removed featured images of children aged 10 years and under, including babies. Over the past four years this figure has risen to 73.5%.
The foundation says this suggests content is becoming more extreme and all reports to the IWF are assessed by a team of analysts who have an exemption within the law to enable them to view potentially criminal content.
When child sexual abuse content is found and hosted within the UK, it is shared with the police and removed within hours thanks to the responsible actions of the online industry.