Child sex abuse investigators have a new weapon to detect objectionable images on the internet, helping to track down offenders and identify victims.
Internal Affairs Minister Amy Adams says department investigators have helped Microsoft develop a world-first software called PhotoDNA.
New Zealand is one of the first countries to have access to the technology after the Internal Affairs Censorship Compliance Unit worked on it with Microsoft for five months.
Ms Adams says the technology will allow investigators to more quickly detect objectionable images, helping to reduce the trading of child sex abuse images.
She says millions of objectionable images are on the internet and PhotoDNA could help rescue the victims of abuse and find the offenders.
Ms Adams says investigators may have to review more than 100,000 images on a seized computer and the new technology will make the job much faster.
A New Zealand agency fighting child sex abuse is welcoming the new software.
Alan Bell, the national director of ECPAT, says New Zealand has one of the world's highest rates of accessing child sex abuse images and the technology will identify victims and track down offenders.
Mr Bell says a government hotline records 50,000 mouse clicks per day from computer users trying to access illegal sex sites.