New Zealand police are investigating whether to use unmanned aerial vehicles, which would act as spies in the sky.

The vehicles are often small and could be used to take video footage and photos from the air. They are discreet because of their size and have been labelled as "eyes in the sky".

Police in the United States have been given consent to use the airborne drones, while police in the United Kingdom say they see the unmanned cameras "as part of our future". 

New Zealand police say they may also be part of ours.

National Crime Manager Detective Superintendent Rod Drew said police were currently evaluating the use of the vehicles.

A decision would be made in about six months.

New Zealand police have used the drones only once, to canvass the area where the body of Wellington woman Sofia Athanassiou was found in July.

Police used a drone from a commercial company to search Mt Victoria in that case, a spokesman said. 

While the machines have been seen as a crime-fighting tool, there are concerns about their pervasive nature.

Drew told TV3 News that New Zealand police were too busy to be monitoring the general public from the sky.

"We don't have the time to go spy on people for no good reason," he said.

United States police chiefs adopted a code of conduct on the use of the drones earlier this month, the Washington Post reported.

They agreed to let any captured images be open to the public and not to store any images that weren't believed to be evidence of a crime or part of an ongoing investigation.

- © Fairfax NZ News