OTTAWA -- The Conservative government must strengthen review and oversight of security agencies if it plans to beef up spying and police powers, say the federal privacy and information czars.

Privacy commissioner Daniel Therrien and information commissioner Suzanne Legault are also urging the government to avoid trampling civil liberties in trying to ensure the safety of Canadians.

Two former Supreme Court justices who led high-profile inquiries into security matters joined those advising a cautious approach to any expansion of law-enforcement powers.

The Harper government is contemplating new laws in response to the recent attacks that killed two soldiers in broad daylight. Possibilities include making it easier to detain a suspect who has not actually committed a crime and outlawing the glorification of political extremism.

The government introduced long-promised changes this week to strengthen the ability of Canada's spy service to probe terror suspects overseas.

It's understandable that the government would want to consider boosting the powers of law-enforcement and national security agencies to address potential gaps, Therrien said Wednesday at a news conference.

But any new measures should be accompanied by a beefed-up role for the watchdogs who keep an eye on spies and police, he added.

"It's important to ensure that our government institutions have the correct tools to address risks," Therrien said.

"But it is equally important that the activities of these agencies be the subject of surveillance and monitoring by independent third parties so that we ensure as a society that these activities are undertaken in a lawful manner."

Legault, an ombudsman for users of the Access to Information Act, said Canadians need appropriate information to make intelligent decisions about the necessary level of security. But most activities related to security and intelligence are shrouded in secrecy.

"The government actually has a lot of information, but Canadians and parliamentarians usually have limited information," she said during the news conference. "I think we have to seriously review the entire oversight framework around intelligence and police enforcement activities."

Therrien highlighted long-standing recommendations by judge Dennis O'Connor, who examined the torture of Ottawa telecommunications engineer Maher Arar in a Syrian prison over false terrorism accusations.

O'Connor's 2006 report advocated allowing national security watchdogs to exchange information and conduct joint investigations. He also recommended a co-ordinating committee that would include various security watchdog chairs to ensure seamless handling of complaints and probes.

"These recommendations were made eight years ago," Therrien said. "There's no reason why the government can't act on this now."

Asked about the recommendations Wednesday in the House of Commons, Public Safety Minister Steven Blaney would not say why the government had ignored them. He said the bill tabled this week would enhance oversight by clarifying the Canadian Security Intelligence Service's powers.

Speaking at a conference Wednesday on the 10th anniversary of the Arar case, O'Connor declined to comment on the government's lack of action on his oversight recommendations, saying judges who preside over inquiries "should not participate in the debate" that ensues.

There should be a formal means of following up on inquiry recommendations, said Frank Iacobucci, a retired Supreme Court judge who looked into the cases of three other Arab-Canadians detained in Syria. All too often, such reports "just gather dust on the shelves," he said during a panel discussion.

Former Supreme Court justice John Major, who issued an exhaustive report four years ago on the 1985 Air India jetliner bombing, was critical of the Harper government's apparent rush to introduce new laws following last week's soldier killings.

"It's a knee-jerk reaction because I think the government feels they have to do something," he said after the panel. "The impetus is to act quickly, and sometimes not so wisely."

Iacobucci said he was also wary of "rushing to change laws immediately" after a dramatic event.

Legault and Therrien joined provincial counterparts from across the country in a joint statement Wednesday recommending "effective oversight" be built into any new legislation to bolster law-enforcement agencies.

It also advocates an "evidence-based approach" to considering the need for new measures, an "open and transparent dialogue" on whether they are necessary, and, if so, discussion about their nature, scope, and impact on rights.

RCMP Commissioner Bob Paulson indicated this week the threshold for obtaining some information about terrorism suspects is too high.

Therrien reiterated his concerns about existing federal legislation -- ostensibly to deal with cyberbullying -- that would lower the barrier for police access to some personal data.

The bill contains new powers under which sensitive information would become accessible to authorities based on a "reasonable suspicion" of wrongdoing, a lesser standard than the constitutional default of "reasonable and probable grounds" to believe an offence has taken place.

"If there is a lower threshold," Therrien said Wednesday, "there would need to be some fairly strong demonstration that it is required."