In a bid to drive paedophiles away from its service, Facebook has announced to introduce a new technology which will automatically trawl photos posted by users for child abuse.

The popular social networking site, which claims to have more than 500 million users, has now partnered with Microsoft and will implement its PhotoDNA technology, designed to identify and remove images that exploit or endanger children.

Run by the National Center for Missing and Exploited Children (NCMEC), the PhotoDNA technology creates a "blueprint" of an inappropriate or offencive image and can search through billions of other images to locate photos with similarly inappropriate features, the Daily Telegraph reported.

According to Bill Harmon, a lawyer in Microsoft's digital crimes unit, PhotoDNA detects child pornography with "zero false positives".

"Some images become 'popular' and are used time and time again -- making good targets for the PhotoDNA program," he said in a post on the Microsoft blog.

Facebook was heavily criticised over its child protection efforts by Britain's Child Exploitation and Online Protection Centre (CEOP), the police agency responsible for tracking down paedophiles online.

It followed the murder of 17-year-old Ashleigh Hall, who was lured to her death by a 33-year-old man who posed as a teenager on the dominant social network.

PhotoDNA is just the latest of several safety initiatives launched since by Facebook.

Microsoft has already implemented the system on its Bing search engine and SkyDrive online storage service, and says it detected more than 1,500 illegal images on the former and more than 1,000 on the latter.

"Even though NCMEC is a US-based organisation, we found image matches on our services stemming from abuse that has occurred across many countries, including the US, UK and Brazil among others," said Harmon

"We hope that Facebook's adoption of PhotoDNA serves as a springboard for other online service providers to take advantage of the opportunity available through NCMEC's PhotoDNA program and, in fact, we know that others are exploring the possibility right now," he added.