Websites containing images of child abuse will be flagged up to internet users with a clear message explaining why the site they are trying to access has been blocked.
The new system being implemented by BT is the latest attempt to tackle the existence of these images online. It is believed to be the first of its kind in the country.
Currently, when a user tries to access a web page on the Internet Watch Foundation's list of those identified as containing images of child sexual abuse, they are shown an "Error 404" message.
But now, BT users will be met with a message that reads: "Access has been denied by your internet service provider because this page may contain indecent images of children as identified by the Internet Watch Foundation. If you think this page has been blocked in error please contact iwfenquiriesbt.com."
The internet service provider began blocking illegal images of child abuse almost a decade ago, and is believed to have been one of the first to do so.
The availability of child abuse images online has become a high-profile issue in recent months, following a handful of child murder cases in which pornography played a part. Mark Bridger, who murdered five-year-old April Jones, and Stuart Hazell, who killed 12-year-old Tia Sharp, were both found to have accessed child and violent pornography sites.
Some experts argue that there is a clear connection between their use of these sites and their actions.
Speaking at a Westminster eForum on protecting children online, Tory MP Claire Perry, Prime Minister David Cameron's adviser on the sexualisation of childhood said: "We've had a couple of appalling child murders.
"We always knew that it was going to happen, that there would be, whether it was causality or correlation, that there would be information or images found on the computers of those who went on to rape, abuse and murder children."
Ms Perry, along with Mr Cameron and Culture Secretary Maria Miller are due to meet with Google and other internet companies next week to discuss what further action can be taken.
The Child Exploitation and Online Protection Centre recently released research which suggested that more than half of those who view child abuse images go on to commit some form of abuse themselves.