According to a report in BBC on Monday, images of young girls in their school uniform or swimsuit and which are actually innocuous, are swapped on Twitter to promote them as child pornography.
"Some have been taken by the girls themselves. It's not clear whether they have then sent them to a boyfriend who's uploaded them... others appear to have been ripped from their social media sites," BBC quoted Joseph Cox, a freelance journalist writing for Motherboard, as saying.
Cox found on Twitter that some users were asking each other to trade the similar pictures and made explicit comments on them.
Twitter's policy on this issues states that when they are made aware of such content that promotes child pornography, they remove it from the site without any further notice. Also, the user faces a permanent ban for such actions.
The report quoted Twitter as saying that they do not tolerate child sexual exploitation, and that they are working with authorities and organisations including the Internet Watch Foundation in the UK to combat the exploitation of children.
"There was a minimum 14,000 accounts involved in the creation, distribution or retweeting of child porn," the report quoted an American woman saying, adding that the victims are girls as young as five, and definitely under 15.
In 2011, Reddit closed down a forum called "Jailbait" that it had similar issues with.