CREDIT: Victoria Times Colonist Reports in the United States suggest the National Security Agency, the world's most advanced electronic surveillance operation, has been collecting details of billions of domestic phone calls.

OTTAWA -- Canada's electronic spy agency says citizens need not worry their phone calls are secretly being tracked by the government -- a reality Americans woke up to on Thursday.

Reports in the United States suggest the National Security Agency, the world's most advanced electronic surveillance operation, has been collecting details of billions of domestic phone calls. Advanced computer systems mine the data for suspicious calls and patterns, and then flag them for further investigation if deemed warranted.

The raw information was first handed over by three of the country's biggest telecommunications companies at the request of the government following the Sept. 11, 2001, terrorist attacks, USA Today reported.

The revelations have since unleashed a political firestorm in Washington.

A spokesman for Canada's Communications Security Establishment, a cryptologic agency embedded in the Department of National Defence which works closely with the NSA, insisted no such program exists here.

"My main message is that CSE collects foreign intelligence, and we do not have any type of domestic surveillance program," Adrian Simpson said.

Although the CSE is allowed to intercept telephone calls involving Canadians, he said, it can only do so under very specific circumstances.

At least one party must be outside the country, and the information mustn't be available by any other means.

CSE doesn't require a warrant to intercept, but a ministerial authorization must be signed.

Simpson said CSE must show the value of the information justifies the means of collection, and activities are subjected to various privacy safeguards.

As with the NSA, little is known about the CSE or its activities. One of the first senior officials to speak publicly about both was a Canadian spy employed by the latter for 20 years.

In an interview with the CBS program 60 Minutes six years ago, Mike Frost suggested countries can, and do, circumvent domestic laws by asking other countries to spy for them.

Asked whether that was a realistic scenario Friday, Simpson said "no."

He did say, however, that the two agencies work very closely together and with allies such as the U.K., Australia and others.

It was first confirmed in 2000 that Canada is a key participant in a global intelligence network capable of intercepting all kinds of communications, from telephone calls to encrypted e-mail.