TORONTO - Ontario's privacy commissioner is launching an investigation into the installation of thousands of security cameras throughout Canada's largest public transit network following a complaint by an international privacy watchdog that the system would violate the privacy of Toronto commuters.

London-based Privacy International filed the complaint with the privacy commissioner Wednesday afternoon, disputing the Toronto Transit Commission's claim that the $21-million project would reduce crime levels and terrorism threats, and arguing that transit officials have shown "contempt" for Canadian privacy law.

"Privacy International believes that the installation of cameras on the scale proposed by the TTC fundamentally violates privacy law," the complaint states.

"In the absence of a compelling case for public safety the program is unnecessary and disproportionate. It also appears to be inappropriate and poorly considered used of resources."

The TTC, which provides 1.4 million rides each weekday, is in the process of installing up to 10,000 security cameras in its buses, streetcars and subway system, adding to its current network of about 1,500 cameras.

The system, which was approved by the TTC last spring and is expected to be operational by June, will be capable of snapping photos and recording video - and in some cases, audio - of any of the TTC's daily riders. The federal government kicked in $6.5 million for the project.

TTC chairman Adam Giambrone defended the system Wednesday, saying the information is centrally collected and accessible only to police, and that the cameras are part of larger security plan that involves such measures as increasing the number of transit constables.

"We were the last of the major transit authorities in North America and Europe - who are way ahead - to install a major camera program. So clearly, the consensus out there is that this is a positive," he said.

While Giambrone said he personally believes the system will work, he acknowledged that the cameras won't necessarily deter many acts of violence.

"But they are a tool for police, they make people feel safer and their results have been proven over the last year, when we've actually been able to use them to make some arrests and some very serious crimes that occurred on the TTC," he said.

However, there's little evidence to support the claim that such surveillance significantly reduces crime levels or the threat of a terror attack, said Simon Davies, a privacy expert and director of Privacy International.

Studies have shown that many recordings from surveillance cameras aren't of sufficient quality to even identify suspects, he points out. Taxpayers will also be saddled with the costs of maintaining the system.

"Very often what happens is that authorities become mesmerized by the technology," he said in an interview from London.

"It makes governments look good, it makes public service employees feel that they're on the cutting edge, but the bottom line is that within a year, the crime figures usually return to normal, and the expenditure has gone to waste."

A report evaluating a pilot project on the Berlin subway testing the effectiveness of 24-hour surveillance in reducing crime revealed that the video surveillance actually led to a small increase in crime, Davies said.

"I'd like to know why Toronto would be any different," he added. "It's using exactly the same technology in the same environment. But where was the acknowledgment by the TTC that this independent study had produced those conclusions?"

The TTC has also failed to establish beyond a reasonable doubt that there is a public-interest justification for the project and did little to publicize plans for the project before implementing it, the organization states in its complaint.

The TTC's justification in installing the cameras will be one area the privacy commissioner will investigate, although it's too early to tell how long the investigation may take, said Bob Spence, a commission spokesman.

"We're looking at exactly why they're putting up cameras, are they putting up signs so people are aware of the cameras," he said in an interview from Hamilton.

"We'll look at all aspects of the complaint."