The Conservative government tabled legislation Monday aimed at expanding the powers of Canada's spying authorities, arguing the new law is needed to combat terrorism.

Bill C-44, dubbed the Protection of Canada from Terrorists Act, gives the Canadian Security Intelligence Service new powers, such as the ability to monitor suspects outside of Canada and protection for CSIS informants.

The Opposition New Democrats were cautious in their initial reaction. NDP public safety critic Randall Garrison said he first wanted to study the bill but expressed concerns about the impact on judicial proceedings.

"We'll be looking at all of that in the days to come," Garrison said in a statement.

Bill C-44 was tabled by Public Safety Minister Steven Blaney and comes after an armed man launched an attack in Ottawa, killing a Canadian soldier at the National War Memorial and storming Parliament Hill's Centre Block.

Two days before that attack, another soldier, Patrice Vincent, was killed when a man ran him down in a parking lot near Montreal. Law officials shot and killed both suspects.

Authorities said both attackers are believed to be "radicalized" sympathizers of Islamic militants abroad.

A release from Blaney's office said Bill C-44 will help Canada co-operate with other nations to monitor potential threats.

"Techniques used by CSIS may include, among others, searches of a target's place of residence, analysis of financial records, or telecommunications intercepts," it said.

David Christopher of the Internet rights group OpenMedia, which opposes the legislation, said he suspects the government will strengthen the bill, noting it was stamped last Tuesday -- a day before the attack in Ottawa.

"That would indicate that the government haven't in fact amended this legislation -- tightened it up or made it stronger -- in light of last Wednesday's events," Christopher said. "I'm guessing that (changes) will take shape in some future legislation."

Christopher's group has started an initiative to gather public input to bring to the government in an effort to help shape Canada's security measures from a pro-privacy point of view.

There will be more analysis in the days ahead about the implications of the bill, he said, adding he is concerned about the broader reach of the bill when it comes to Internet spying on Canadians with the potential help of nations like the United Kingdom, U.S. and Australia.

Jeremy Nuttall is The Tyee's Parliamentary reporter.