Apps that direct paedophiles to illegal child porn sharing groups have profited from unwitting adverts from tech giants including Amazon, Microsoft and Dyson.
The apps were available on Google’s play store until they were removed over Christmas by the company after it was alerted to their role in fuelling illegal child porn online.
Some of the apps have been downloaded more than 100,000 times and will still be functioning on the phones of people who purchased them, according to AntiToxin Technologies, an Israel-based child protection organisation that uncovered the trade.
They direct people to groups on WhatsApp, which Facebook owns, where hundreds of paedophiles openly share illegal child porn, most of which is recently produced and largely comprising videos of children, says AntiToxin.
By linking to Google and Facebook ad networks, the apps were able to financially support their activity by carrying adverts from household names including Amazon, Microsoft, Motorola, Sprint, Sprite, Western Union, Dyson, DJI, Gett, Yandex Music, Q Link Wireless and Tik Tok.
Google and Facebook say they have now taken action against the apps and reimbursed advertisers who had unwittingly funded the apps.
However, AntiToxin says illegal child porn sharing groups are still being run by paedophiles on WhatsApp. Roi Carthy, its chief marketing officer, said public chat groups should be shut down until WhatsApp had established a system to prevent paedophiles accessing or using them.
He warned that the phone numbers of people in public groups were visible and were not encrypted, putting young users at risk. “‘WhatsApp is not doing enough and is hiding behind the encryption canard,” he said.
Tony Stower, NSPCC’s Head of Child Safety Online, said: "It should be obvious to advertisers that they should not support the spread of these vile images.
"Everyone has a part to play in preventing child abuse and these advertisers, with their huge marketing power, should use their financial muscle to insist tech companies tackle child sexual abuse imagery
“If social media sites fail to do so, they should boycott them until they get their act together and take the issue seriously."
Google said: “Google has a zero tolerance approach to child sexual abuse material and we thoroughly investigate any claims of this kind. As soon as we became aware of these WhatsApp group link apps using our services, we removed them from the Play store and stopped ads.
“These apps earned very little ad revenue and we’re terminating these accounts and refunding advertisers in accordance with our policies.”
Facebook said: “We do not support the monetization of harmful content. We disable apps and withhold revenue from accounts found to be in violation of our policies or that are removed from third party app stores”.
Microsoft and Dyson declined to comment. Amazon was contacted on Sunday but had not responded by the time The Daily Telegraph went to press.