And an overwhelming majority of the content – 93 per cent – featured girls rather than boys.
One video described in the report featured a girl aged about seven who was heavily made up and dressed in underwear exposing herself.
Students explore the risks and responsibilities of carrying out romantic relationships in the digital world.
" It went on: “The finding that 667 of the images and videos assessed depicted children aged 15 years and younger, with 286 of these depicting children assessed as being 10 years and younger indicates a disturbing trend for younger children to be producing sexually explicit content which is being distributed online.
“Of particular concern is that the young people depicted took no steps to conceal their identity or location, even in many cases using their real names “In some instances, it is apparent that this content is being knowingly created to appear on public websites.” Nine out of 10 of the explicit videos and images were created using a webcam, usually on a home computer, which the study said challenged the traditional view of such content being produced on mobile phones.
"Comments made in relation to this video on the site on which it had been posted say this video is an example of a 'sextortion' video, whereby a child is blackmailed on the basis of sexual content they have shared with the blackmailer," said the report.
"If the child refuses to create more, the blackmailer will distribute the original content publicly.
The girl says: "Mum might see it and get worried and you know, like, delete my account." Another video of "extremely sexually explicit" acts featured a girl aged about 12.
"In some instances it was clear that the children depicted were aware and intended that the content they were creating should appear on public internet sites," said the report.“Traditional definitions of ‘sexting’ and ‘self-generated sexual content’ have focussed on the use of mobile devices such as phones as being the primary method for creation and onward distribution of the content,” it said.But an IWF spokesman said in some cases the material was secretly recorded on internet video calling services and then posted by a third party.In another video described in the research a girl aged about 10 is "crying and clearly extremely distressed" as she repeatedly shakes her head at an unknown individual communicating with her over the internet, before she strips naked.After discussing the video, students create an ending to a story about a girl who is being pressured to “sext.” They brainstorm ways to avoid sexting and to use digital technologies responsibly in romantic relationships.Online safety group the Internet Watch Foundation (IWF) and Microsoft, the technology giant, which worked together on the new research, said they identified nearly 4,000 images and videos in a snapshot covering three months last autumn.