THE New South Wales Government is quietly compiling a mathematical map of almost every adult's face, sharing information that allows law enforcement to track people by CCTV.

Experts said yesterday few people realised their facial features were being recorded in an RTA database of drivers licence photos that the Government has allowed both state and federal police to access, The Daily Telegraph reports.

The federal body CrimTrac has asked NSW for its database so it can be mined nationally by police using the facial recognition information contained in it.

University experts in facial recognition said the correct match rate was as low as 90 per cent, meaning the names of people with faces sharing a similar structure to criminals could be returned in searches.

Dr Carolyn Semmler from the University of Adelaide said police wanted to eventually use facial recognition in smart CCTV cameras allowing people to be tracked anywhere there was a camera.

Some airports, such as Singapore, employ facial recognition technology and the US is considering using it at border crossings.

"Police hope that at some point an individual can be tracked," Dr Semmler said yesterday.

Professor Sowmya Arcot from the University of NSW said a "matrix of numbers" based on features and the distance between facial structures was derived using an algorithm applied to a photograph of a face.

That could then be matched to other faces stored in a database.

NSW Opposition police spokesman Mike Gallacher said most people were unaware their face had been mapped when they applied for or had their licences renewed, allowing them to potentially be tracked.

"Over 20 years ago we had a debate about the Australia card and the people of this country showed where they stood in relation to the government knowing people's movements," he said.

"The push for this into the future has far greater ramifications than some old Australia card.

"I have a concern about a lack of public debate."

The RTA began compiling its facial recognition database last December.

Roads Minister David Borger said it would be shared with other government agencies.

"While the facial recognition system is in its early stages, the RTA will co-operate with other agencies wherever possible," he said.

"The RTA already provides information to the police, and will co-operate with other state or federal law enforcement agencies."

He said the technology was also preventing fraud and stopping people obtaining multiple licences.

A spokeswoman for CrimTrac said its board of management had granted approval for a project proposal for a nation facial recognition capability.