Smile - you're on camera all over Auckland City

They can read the hands on a watch from several streets away or spot someone on Mt Eden from the side of the Harbour Bridge.

Auckland is covered in covert cameras, a Big Brother operation spying on residents 24 hours, seven days a week, from thousands of closed circuit TVs (CCTVs) operated by police, the council and private business operators. On one Queen St corner alone, 15 separate cameras watch pedestrians cross the street. Though the cameras are a deterrent and can provide clues for inner-city crimes - most notably in this month's kidnapping and murder of Chinese student student Wan Biao - privacy experts say there are dangers.

Private investigator Danny Thompson of Auckland Investigations said people would be shocked to learn their every move can be tracked by at least 1000 cameras in the downtown area.

A camera on top of the Sky Tower is so powerful it can focus on car licence plate numbers and another on the Harbour Bridge can zoom in on people on the summit of Mt Eden.

With nearly 50 cameras along Queen St, Mr Thompson said police had an impressive wall of screens to monitor hotspots and keep an eye out for criminals.

"It blew me away. There's a mass of screens which they can flick through, and police quite often pick up wanted criminals walking through town," he said.

There are nearly 65 cameras monitored by police in the CBD, including Karangahape Rd, Queen St, Aotea Square, Vulcan Lane, Britomart and Viaduct Harbour.

When 111 callers report crimes in shops, police can track the suspects' to other parts of the city.

"Some of our more familiar faces know where the cameras are and give us a wave," said Craig Fisher, acting sergeant for the Downtown police.

The camera network is shrouded in secrecy. The council and police refused to give exact locations, citing the potential for vandalism if the public knew where they were.

But privacy lawyer John Edwards said the locations of the cameras should be made public. "The cameras are pretty troublesome. I think people have a right to know where cameras run by public authorities are."

Police say their guidelines for use are strict - private properties, such as hotel room windows, are blanked out and footage is stored on computer hard drives for only a month before being erased.

Although an individual could be tracked for the entire length of Queen St, Mr Fisher said there were no breaches of privacy. Only authorised operators could operate the cameras and, other than in an emergency, couldn't zoom in on or track a member of the public, or look through windows. Footage was used only for criminal inquiries, police training and crime research.

As technology becomes cheaper and more effective, local authorities around New Zealand are placing more cameras in public places such as parks and beaches to deter vandals and taggers. Privacy Commissioner Marie Shroff said the need for cameras to keep people safe should be balanced with the potential for an invasion of privacy.

Chris Gasson, traffic and roading manager at Auckland City, said the 35 cameras used by the traffic management unit (TMU) were also monitored by police, preventing misuse. And the TMU's guidelines were in line with police standards.

But private security cameras aren't as well regulated. Companies don't have to put up warnings about where cameras are.

Mr Edwards said many cameras probably skirted privacy laws but nothing could be done until people could prove they had been harmed by use of footage.

Ms Shroff said she had received no complaints about security cameras in public areas, but people often asked about their neighbours' rights to install personal security cameras.

A recent Privacy Commission survey showed only a third of respondents were worried about being caught on camera, but there was concern about what the footage could be later used for.

Ms Shroff said people needed to realise that security cameras were no guarantee of safety. "Just because a camera can see you, the cavalry isn't necessarily going to come running and save the day."