The Canadian government is expected to lower the threshold for preventative arrests and restrict the movements of alleged radicals as part of legislation to fight terrorism.

Ottawa is also looking to revise the Passenger Protect system to make it easier to keep individuals from boarding planes.

Prime Minister Stephen Harper recently promised a bill soon that will address shortcomings in the tools that security agencies and law enforcement have to thwart terror attacks.

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A review Ottawa undertook in the aftermath of the October attacks on Canadian soldiers, when a gunman also stormed Parliament, flagged gaps in the tools available to fight extremists.

For example, under the current no-fly list regime, the only way authorities can keep someone off a plane is if they can prove the person represents a direct threat to that particular plane and passengers.

Ottawa wants to be able to keep suspected extremists from flying if the authorities believe they represent a threat – even if the danger is not to the immediate plane that the individuals want to board.

In the case of Michael Zehaf-Bibeau, the gunman who killed a soldier and breached Centre Block, the RCMP had tried in vain to get a peace bond last summer that would have restricted his movements, sources say.

When Mr. Zehaf-Bibeau applied for a passport to travel to Syria, the RCMP were contacted to conduct a background check. The Montreal man's passport application wasn't rejected, but it hadn't been approved because the investigation was continuing to determine whether he should receive one. Investigators believe the passport issue was part of his motivation for the shooting.

The Mounties failed to get a peace bond because the public prosecutor said they needed more evidence.

The government isn't faulting the public prosecutor or the RCMP and instead wants to retool the law.

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The Conservatives have been weighing new tools to deal with citizens who openly support terrorist attacks on Canadians or back groups that promote this goal, as well as additional powers or measures for police and agencies that monitor terrorist groups.

Critics have already raised concerns that Ottawa could trample civil rights by overreacting to attacks in Canada and abroad.

The Conservatives maintain they will ensure the planned new anti-terrorism measures do not go too far.

"We want to make sure that we get a balance – that we protect the rights of Canadians and also the security of Canadians. We must protect both," Mr. Harper said this month.

Ottawa has already signalled it will give government departments and agencies explicit authority to share private or confidential commercial information in legislation to be introduced shortly after the Commons resumes Monday.

Sources familiar with the plans say a government review of the killings found problems that inhibit the free flow of useful information between departments and security agencies.

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The changes would allow information submitted in passport applications and on the movement of items such as automatic weapons, GPS systems or controlled goods that could be used in terrorist attacks to be shared with Canadian security agencies.

Ottawa is also planning a more robust government-financed campaign to thwart radicalization in young people. The RCMP have started a program, but Ottawa is looking at doing more.

Right now, departments or agencies might have the discretion to circulate data, but often hold back for fear of breaching privacy legislation that protects individuals or corporations.