VANCOUVER -- Canada's intelligence chief stepped out of the shadows yesterday to warn that despite "some successes" in the war on terrorism, al-Qaeda and other extremist groups are proving themselves a persistent foe.

"If anything, the lessons of recent years lead to the conclusion that they are not going away soon and that we and our allies need, therefore, to retain the focus on these issues," said Ward Elcock, director of the Canadian Security Intelligence Service.

"Now is not the time to declare victory and rest on our laurels," Mr. Elcock said in a speech to the Canadian Association of Security and Intelligence Studies, which is holding its annual conference in Vancouver.

Mr. Elcock appeared to be responding to a growing backlash against Canadian counter-terrorism measures from interest groups that call them an overreaction and an intrusion on civil liberties.

Canadian Muslim organizations and refugee lobbyists have been particularly critical of national security policies such as the immigration law that allows Ottawa to deport foreign terrorists to their homelands.

Patrick Smith, a Simon Fraser University political science professor, said Canada has gone too far in response to 9/11, resulting in a loss of civil liberties and a win for the terrorists. "We've lost the balance."

But Mr. Elcock defended Canadian counter-terrorism policies, saying they balance security needs with civil liberties, and cautioned that the threat posed by terrorists remains "persistent and evolving."

Terrorists "have proven their determination to exploit trans-boundary movements of people, of money and of goods." They have also shown a "growing interest" in acquiring nuclear, biological and chemical weapons, he said.

The threat posed by weapons of mass destruction was a recurring theme at the conference, titled Homeland Insecurities: The Shifting Borders of Security, Intelligence and Law Enforcement.

Douglas Ross, Canada's former disarmament ambassador, described a scenario in which terrorists might set off a nuclear bomb in Canada to frighten the United States into changing its policies in the Middle East.

"In that sense, we are not at the centre of the bull's eye, but we are in the inner circle of the target," he said, adding that a nuclear suitcase bomb would be a thousand times more powerful than the Oklahoma City bombing.

"This isn't theoretical. This is real. This is a risk." He said Canadian foreign policies fail to reflect that "we live in a very dangerous world. Many Canadians, especially those in positions of political authority, don't recognize that fact."

Richard Fadden, president of the Canadian Food Inspection Agency, said terrorists could easily taint the food supply. Anyone could walk out of a university lab with enough toxins to cause mass disruption, he said. "It's very, very easy," he said. "This is an area where I think we have to do a little bit more than we have in the past."

Biological terrorism, such as the anthrax attack that struck in the United States in the fall of 2001, is also a major concern, but the impacts of such an attack are mostly unknown, said George Betts, an intelligence analyst in the Privy Council Office.

While biological agents could be extremely deadly, they are also difficult to obtain, manufacture and distribute, he said. But they remain a worry, and terrorists know that.

"We already feel vulnerable to outbreaks of disease," said Mr. Betts, who specializes in weapons of mass destruction. "The thing that raises our concern is that terrorists are aware of the vulnerability."

Mr. Elcock said Canada had no intelligence that would have indicated the 9/11 attacks were coming, but he said Canadian agencies have been heavily involved in the investigations that have followed. U.S. requests for Canadian intelligence information on Sunni Islamic terrorists jumped by 300% after Sept. 11, he said.

"Sept. 11, 2001, found the service with assets that allowed us to make a contribution to the ensuing international manhunt for people who inspired, funded or otherwise supported the Sept. 11 attackers," he said.

Mr. Elcock retires as the CSIS director next May after 10 years as Canada's senior intelligence officer. Names being floated as possible replacements include Margaret Purdy, former head of the Office of Critical Infrastructure Protection, and Paul Kennedy, Canada's senior assistant deputy solicitor-general.

sbell@nationalpost.com