OTTAWA -- A federal watchdog says Canada's electronic eavesdropping agency did not invade the online activities of Canadians during a controversial study of wireless communication at airports.

The independent body that monitors Communications Security Establishment Canada says the spy agency's effort wasn't about mass surveillance or the tracking of Canadians.

A CSEC document obtained by CBC -- originally leaked by former U.S. spy contractor Edward Snowden -- suggested information was taken from an unidentified Canadian airport's free Wi-Fi system over a two-week period to conduct the trial.

In a new posting on its website, the CSEC watchdog says it has since questioned eavesdropping agency employees about the project and examined the results of the activity in question.

It says the effort was used by CSEC to understand global communication networks and was not directed at Canadians or people in Canada.

The watchdog's office, led by Quebec judge Jean-Pierre Plouffe, says if CSEC were tracking the movements or online activities of people at a Canadian airport, that would be illegal.

The comments echo those of CSEC chief John Forster, who told a Senate committee shortly after the CBC story aired that CSEC was merely collecting electronic metadata -- or data trails about messages -- and not the actual content of those messages and calls.

Forster said the spy agency was trying to build a mathematical model to help determine a communication pattern at a public location, in this case an airport.

The May 2012 CSEC presentation leaked to CBC says the project could help security officials locate a kidnapper making ransom calls.

Ottawa-based CSEC monitors foreign computer, satellite, radio and telephone traffic of people, countries, organizations and terrorist groups for information of intelligence interest to Canada.

CSEC is forbidden from targeting the private communications of Canadians such as emails and phone calls. However, metadata is not considered private communication for the spy service's purposes.

The watchdog's conclusions are unlikely to assuage civil libertarians and privacy advocates who say CSEC's metadata monitoring is worrisome because even such seemingly innocuous routing codes can reveal much about someone, such as their location and who they are contacting.

Forster has denied CSEC uses metadata to build profiles of Canadians. Metadata actually helps the agency screen out the content of Canadian messages, he said.