Databases will be used to prevent the distribution of child pornography
Thousands of child pornography images will be collected into a database to prevent further distribution, a group of online companies has announced.
The move is part of an effort by the newly formed Technology Coalition, set up to fight child porn in the US.
The coalition is made up of five online giants, including Yahoo and Microsoft, and the National Center for Missing and Exploited Children (NCMEC).
The group have also pledged technology and $1m (£550,000) to the fight.
"These leading companies have a wealth of expertise and technological tools that can help protect children and reduce the proliferation of sexually abusive images of children," said Ernie Allen, president and CEO of NCMEC.
"Similar tools have been used to protect users from other internet-related threats, such as spam, phishing and viruses. Now they can also be applied to this fight against child pornographers," he said.
The coalition comprises online service providers Microsoft, Time Warner AOL, Yahoo, Earthlink and United Online and the NCMEC.
The creation of the group was announced as a number of companies, including those forming the new coalition, presented evidence to the US Congress about their efforts to combat child pornography online.
The US government has put growing pressure on companies to tackle the problem.
Alberto Gonzales has asked for laws to be changed to tackle child porn
In April this year US Attorney General, Alberto Gonzales, said that the net had created an "epidemic" of child pornography.
In response, he announced proposed changes in the law under the Child Pornography and Obscenity Prevention Amendments of 2006.
The proposals were sent to Congress and included new laws that would require Internet Service Providers (ISPs) to report child pornography.
Mr Gonzales also said that he was investigating ways to ensure that ISPs retain records of a user’s web activities to track down offenders.
Although the coalition does not directly address the issue of retaining records it indicates that the online industry is willing to co-operate with the US government.
The Technology Coalition will develop new and existing technologies to help detect child abuse on the web.
It will work with industry and law enforcement agencies to catch people who distribute child pornography and deter others from doing so.
Google say they have a zero tolerance approach to child porn
The first project planned is for a database of images. The coalition plans to give each image, collected by the NCMEC, a unique digital fingerprint.
Participating companies could then scan user’s images for the fingerprint to identify offenders.
For example, AOL plans to check e-mail attachments that are already scanned for viruses.
"It may not be possible to eradicate all threats to children online, any more than it is possible to protect children from all threats in the physical world," said John Ryan, Chief Counsel of AOL.
"However, by better leveraging 21st century technologies, we believe it is possible to increase the chance that child predators will be caught and provide a deterrent to those who would be tempted to exploit children on the Internet."
Other companies presenting evidence to Congress included Google.
The search giant was attacked for showing millions of sites when explicit search terms were used.
For example, "pre-teen," "sex" and "video" yielded 2.9 million results on Google.
Writing on the official Google blog, Nicole Wong, Associate General Counsel for the company, said: "Google has a zero-tolerance policy on child pornography."
"When we become aware of child pornography anywhere in our search engine or on our site, we immediately remove and report it to the appropriate authorities."
She said the search engine produced so many results for the term "pre-teen" because the hyphenated version of the phrase was not flagged up by the site.
The mistake has now been corrected, she said.