The head of Canada's electronic-eavesdropping agency says he "can't really disclose" what kinds of access it could have to data flowing through Bell, Rogers and Telus.

As John Forster fielded questions from MPs this week, the spymaster stressed that Communications Security Establishment Canada is still banned from spying on Canadians. Yet he was less definitive about CSEC's potential relationship to the "Big Three" telecommunications companies.

Questions about the fast-growing, $500-million-a-year spy agency arose this week at a parliamentary defence committee. Today, it collects and stores data in unfathomable volumes, but never says precisely how it gets the material.

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Globally, concerns are mounting about governments forcing telecommunications firms to hand over bulk records that can be searched for intelligence leads. U.S. President Barack Obama last month reined in a sweeping spy program that secretly obliged the country's phone companies to hand over citizens' call records.

No such practises are known in Canada. But the Conservative government recently introduced a bill that would prevent anyone from suing banks and phone and Internet companies that hand records over to government authorities without warrants.

Once-ironclad laws against any kind of domestic interception by CSEC began to be loosened in 2001.

Noting the agency was recently caught tracking devices that had passed through a Canadian airport, New Democrat MP Jack Harris posed blunt questions. "Do you have … direct access through electronic means from your headquarters to information on the Bell, Rogers, and Telus networks," he asked.

"… Our focus is foreign intelligence collection," Mr. Forster replied.

"… I'm asking what access you have," Mr. Harris said.

"We collect in areas around the global networks where we're going to be most successful in finding our foreign targets," Mr. Forster said, adding, "I can't really disclose our methods and capabilities in that collection."

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He disagreed with Mr. Harris's suggestions that CSEC had built "backdoors" into corporate systems.

A transcript of Thursday's meeting was released on Friday. Representatives of the telcos could not make any additional comments immediately.

A spokesman for CSEC said the agency cannot discuss its information gathering.

"As you know, information on our methods, techniques and capabilities is highly classified, and to reveal details about them would be a violation of the Security of Information Act," Andrew Mclaughlin said. "It would also undermine our ability to provide the government with foreign intelligence, and to protect Canada and Canadians."

Mr. Harris, who was travelling on Friday, sent an e-mail to The Globe and Mail saying he was "not satisfied at all" by the answers.

"My conclusion is that the agency does have access."