Child sex abuse images is rampant on the web as it has become a big business online, according to the UK's Internet Watch Foundation (IWF).
The IWF's annual report discloses that about 450 criminal gangs across the globe are using child sex abuse images to make money, with the 10 most prolific of these accounting for over 650 web pages.
While the report says the industry is not growing despite being well-established online, it also points out that these groups are finding newer ways to distribute these images.
It reveals that content distributors are now using smaller social networks, image-sharing sites, free website hosting platforms and hacked websites to avoid detection.
Moreover, to avoid getting caught they shift their distribution networks frequently between different providers and countries.
Most gangs run a pay-per-view system, charging a monthly fee of about 55pounds for access to photos and videos.
The IWF believes a large part of the commercial material is initially exchanged privately between sex offenders.
"Although internet usage and the volume of content continue to rise globally, we are not seeing a proportionate rise in commercial child sexual abuse material which instead appears to have remained fairly static over recent years," the BBC quoted Peter Robbins, chief executive of the IWF, as saying.
The IWF received more than 38,000 reports about illegal content last year.
The majority of this was either hosted outside the UK or outside its remit.
About 44 percent of the content highlighted to the IWF in 2009 depicted the rape of a child and 23 percent of it featured children below the age of six.
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