The NDP introduced a motion on Thursday to prevent the federal government's controversial amendments to Canada's immigration laws from passing with the federal budget.

The move in the House of Commons comes on the same day a group of immigrant service organizations decried the Conservative government's proposed changes to Immigration and Refugee Protection Act, saying the measures place too much power in the hands of the minister in charge.

The proposed changes, which are embedded in the budget implementation bill, propose giving the minister greater selection powers to limit the number of new immigration applicants. 

Under the proposed amendments, the bill would allow the government to fast-track applications from the types of immigrants it wants, such as skilled workers, and freeze applications from others.

NDP MP Olivia Chow introduced the motion, which "declines to give second reading" to Bill C-50 because it contains policies that "fail to recognize that all immigration applicants should be treated fairly."

NDP Leader Jack Layton said the proposed changes will make it harder for families to be reunited and accused the government of trying to give the immigration minister the "sole decision-making power to shape Canadian society."

"The changes that are proposed here are going to do irrevocable damage to immigrant families," Layton said.

Liberal deputy leader Michael Ignatieff said the government's change of one word in the existing legislation would give the minister the arbitrary power to reject even those who meet all the visa requirements.

The proposed legislation says a visa or document "may" be issued to an applicant who has already been ruled admissible by immigration officers, while the existing law which says a visa or document "shall" be issued.

"You can't have a fair and just immigration system without rules," Ignatieff said. "But with a stroke of the pen, the minister has written fairness and justice out of the immigration system."

Government House leader Peter Van Loan charged the opposition members were "mischaracterizing" the measures, which he said come at a time when Canada's labour force faces critical shortages and needs more, not fewer, immigrants.

The Tories have argued the measures are necessary to reduce a current backlog of more than 900,000 immigration applicants, which has created wait times of between three and six years for even those who meet all the requirements.

But critics have accused the Tories of sneaking the clauses through Parliament via the budget bill without a full and open debate to examine potential concerns over the changes.

"That's putting a lot of arbitrary power in the hands of one person that is subject to change by the whims of the different government of the day," immigration lawyer Amina Sherazee said Thursday during a press conference in Toronto organized by the Ontario Council of Agencies Serving Immigrants.

Tories 'have taken action' on backlog: Van Loan

Van Loan also defended the Tories' overall record on immigration, citing record numbers of immigrants entering the country this year and a 40 per cent reduction in wait times for family reunification cases, as well as the government's apology and settlement to those subject to Canada's head tax on Chinese immigrants.

"When it comes to family reunification, we have taken action," Van Loan said.

Ignatieff, in turn, charged that the backlog had increased by 100,000 people during the 27-month period the Conservatives have been in power.

Immigration Minister Diane Finley has said the measures will be compliant with the charter and will not create a system in which the minister would intervene on a case-by-case basis, but instead offer guidelines to immigration officers working with applications.

The Liberals ensured the vote on Bill C-50, a confidence motion, did not bring down Prime Minister Stephen Harper's government, but the bill must still be debated and sent to committee before returning to the House for a final vote.

Both the Bloc Québécois and NDP voted against the bill.

With files from the Canadian Press