The federal government's rejection of key amendments to legislation that would create a new national security oversight committee will prevent future committee members from doing their job, the opposition argues.

Bill C-22, "An Act to establish the National Security and Intelligence Committee of Parliamentarians and to make consequential amendments to certain Acts," comes up for debate this week.

The government has already given notice it will reject opposition amendments that would have given the new committee powers to subpoena information and to stay on top of ongoing police investigations, and to make it more difficult for ministers to refuse to turn over information.

"If you're going to go through the trouble of creating the committee, you should allow it to do its job properly," Conservative public safety critic Tony Clement told CBC News.

During the 2015 election campaign, the Liberals also promised to repeal the "problematic elements" of bill C-51, the previous government's anti-terrorism bill and introduce legislation that "better balances our collective security with our rights and freedoms."

The new oversight committee was to be at the heart of that balancing act.

The Liberals 'have tilted the balance towards secrecy' - Murray Rankin, NDP critic

NDP MP Murray Rankin, who has been his party's lead on this file, told CBC News the government's changes represent the Liberals' only response to C-51 since they came into power — and that alone would be "disappointing."

But the latest changes have crushed his earlier belief that the "government was serious about oversight."

"The government is watering it [C-22] down to a shadow of what was proposed," Rankin said. "The committee won't be able to do its job."

Clement hit a similar note, saying the proposed changes mean Canada will end up with a "shadow of other oversight committees" that Canada's intelligence and security allies have in place.

Liberals want bigger committee

Public Safety Minister Ralph Goodale said the committee would be able explore "any and every dimension of national security that they want to look at" when he tabled the bill last year.

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Conservative MP Tony Clement says that, without amendments, Canada's national security committee will be 'a shadow' of the oversight bodies of its allies. (Andrew Vaughan/Canadian Press)

Government House Leader Bardish Chagger said in a statement Monday that "the proposed bill establishes a rigorous parliamentary oversight mechanism of national security and intelligence activities.

"The committee of MPs and senators would have a mandate that is distinctly broader than is the case in most other countries. It would be empowered to examine activities across the entire federal government, including operational matters," the statement said.

While the government plans to reject the opposition amendments, it is amending the bill to increase the number of members from nine to 11. If the bill becomes law, the committee would consist of eight MPs and three senators.

Rankin said he is still hoping the government will agree to send the bill back to committee, because otherwise he doesn't see how he could support the bill.