Edward Snowden, the fugitive American who leaked state secrets, wants Canadians to know that anti-terrorism laws are easy to pass but very hard to undo.

"We saw on Friday the Prime Minister of Canada proposed a new law," Mr. Snowden told a teenaged Toronto audience via an Internet link on Monday night.

He told the high school students that they should "always be extraordinarily cautious" and press for answers, whenever governments rely on "fear and panic" to set up powers that can be exercised in secret.

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On Friday, the Conservative government introduced legislation that would empower Canadian authorities to "disrupt" suspected terrorist threats and remove extremist posts from the Internet. At the same time, Prime Minister Stephen Harper has been resisting calls to step up scrutiny of Canada's spy agencies.

Mr. Snowden was speaking to a crowd of more than 1,000 students at Toronto's Upper Canada College via a Google Hangouts link from his exile in Russia. More people watched on the Internet, and it was the first time he directly addressed a Canadian audience.

The event was organized after a student relayed a request to Mr. Snowden through a lawyer at the American Civil Liberties Union. The U.S. government is seeking to arrest Mr. Snowden, who was charged with espionage after he fled the United States in the spring of 2013.

The former U.S. National Security Agency contractor had taken with him a trove of top-secret documents about electronic eavesdropping, which he passed to journalists. The documents are now the subject of continuing leaks.

Students pressed Mr. Snowden to do more to reveal the inner workings of Canada's NSA counterpart, the Communications Security Establishment. Mr. Snowden countered that does not directly engage himself in the reporting process.

Last week, a leaked CSE document revealed that Canadian analysts have been scouring "free file upload" Internet sites in hopes of unearthing manuals related to jihadi activity.

The agency, which collects foreign intelligence signals for Canada, is technically banned from spying on domestic communications.

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Previously, leaks have shown that CSE traced smartphones it had spotted moving through Toronto's Pearson airport

Many of Mr. Snowden's leaks to date have highlighted secret spying collaborations among the NSA, CSE and counterpart agencies in Britain, Australia and New Zealand. The collective is known as the "Five Eyes."

When a student asked Mr. Snowden whether he was satisfied with the tenor of the leak coverage to date, the American said there has been too much talk about his personality, and not enough about Western democracies creating powerful surveillance programs in secret.

"When we talk about the mass media … they create narratives of heroes or traitors which distract from the issue at hand," he said.

"… Whether or not I'm Mother Teresa or Adolf Hitler, that has no bearing whatsoever on the content of the reporting."

The spy agencies have claimed that Mr. Snowden's leaks have caused enormous damage to their ability to protect national interests, but he disputes that.