Police have requested images they believed to be linked with ''non-traffic related offences'' six times since the point-to-point cameras first became operational on Hindmarsh Drive in February.

The use of the speed cameras for general criminal surveillance has drawn criticism from civil liberty campaigners, who claim the government has not been transparent about such uses of the technology.

Images from the cameras are stored for 14 days before non-pertinent data is deleted.

The legislation allows police to use those images to track the movements of cars as long as it is ''reasonably necessary for the enforcement of the criminal law''.

That standard of proof does not require a warrant or court order.

But an ACT Policing spokesman said police must make a detailed formal request for an image they believe is linked to a crime by providing the time, place, date, location and vehicle details to the Justice and Community Safety Directorate.

''An example could be that an aggravated robbery occurs in the vicinity of a P2P camera zone, and by witness accounts, it is identified that the vehicle involved in the commission of the offence travelled along the P2P zone,'' the spokesman said. ''In this circumstance, police could request the image of the vehicle to assist in identifying the vehicle,'' he said.

But Civil Liberties Australia director Tim Vines said the government had not been open about the use of speed cameras for more general criminal surveillance.

He said the public must be made aware what standard of proof police are required to show before they were allowed access to the images.

''If information is going to be collected for a general surveillance purpose, then the government should be upfront about it,'' Mr Vines said.

''It needs to be very upfront about the protocols it has in place, the standard of proof it requires, and what that information can then be used for,'' he said.

Police Minister Simon Corbell said the sharing of images with police was consistent with information privacy principles.

Mr Corbell said the issue was the subject of ''detailed scrutiny'' when the legislation governing the cameras was passed, and was extensively canvassed in public debate.

The point-to-point speed camera network will continue to expand over the next 12 months.

The government is currently in the procurement phase for another set of cameras on Athllon Drive in Canberra's south.

Those cameras are expected to be built by June next year, and should become operational by August.

The forward design study suggested a further eight potential sites for point-to-point technology, including stretches along Gungahlin Drive, William Hovell Drive, Parkes Way, Tuggeranong Parkway and Ginninderra Drive.

Mr Vines described the use of the cameras for broader car tracking as a ''classic case of scope creep'' likely to become more common.