ORONTO - Prime Minister Stephen Harper plans to give Ontario 13 additional seats in the House of Commons, sources told The Canadian Press on Tuesday.

That would increase the province's presence in the Commons to 119 seats from the current 106.

But it falls short of the 18 spots Ontario was slated to receive under previous legislation that died when Parliament was dissolved.

The bill, which was introduced last spring, would have also given seven more seats to British Columbia and five to Alberta.

According to media reports citing sources Tuesday, B.C. will now receive five new seats while Alberta will gain six and Quebec will get two.

The federal government has not confirmed any of the new numbers.

Ontario Premier Dalton McGuinty refused to speculate earlier in the day about the number of seats the country's most populous province could end up with, but suggested that it could be fewer than expected.

McGuinty said he's reserving his judgment on whether Ontario is being shortchanged until he sees the legislation and the formula the federal Conservatives used.

"I think in fairness, we've got to wait for the feds to come forward with a specific proposal — with a bill — and with some reliable data from Statistics Canada so that we can then make an assessment as to whether or not Ontario is being treated fairly," McGuinty said after touring a Toronto hospital.

But there is a "broad consensus" on Parliament Hill that Ontario, Alberta and B.C. are under-represented in the Commons, the premier said.

"We need to address that," he said. "The prime minister made a specific commitment in the campaign that he would address it. I have no reason to doubt that he's not prepared to do that."

The federal New Democrats introduced a bill Tuesday that would give Ontario 18 seats, B.C. seven and Alberta five, as originally proposed by the Tories.

But it would also include a proviso guaranteeing Quebec a minimum of 24.35 per cent of the seats, in perpetuity, regardless of any population decline. The percentage is fixed at Quebec's proportion of the population at the time that Parliament unanimously approved a 2006 motion recognizing that the Quebecois constitute a nation within a united Canada.

"The whole point is to ensure that the political weight that Quebec had at the time that the motion was passed unanimously by the House is maintained going forward, regardless of population," said NDP democratic reform critic David Christopherson.

"This is about nation building ... Let's give real meaning to that (motion) when we're increasing the seats in these three populous (provinces)."

How many more seats the NDP's bill would mean for Quebec won't be clear until latest census data is released but Christopherson estimated it would be about four.

He acknowledged the NDP has been accused of "pandering to Quebec" on this issue. But he argued that seats in the House of Commons have never been apportioned strictly on a representation by population basis. The smaller Atlantic provinces, Quebec and the North have long been guaranteed more seats than their population warrants.

"We're doing this not because it's necessarily popular because there will be eyebrows raised across the country," he said. "We're doing it because it's the right thing to do for Canada."

Harper confirmed last week that he was intent on giving Ontario, Alberta and B.C. more seats to reflect population growth, but didn't say when the legislation might be introduced.

He also said that Quebec's share would be fair based on its population amid reports that he was delaying seat redistribution legislation past the 2015 election because the Tories fear a backlash in Quebec.

Quebec wants a guarantee that it will continue to hold 24 per cent of the chamber's seats. It currently has 75 of the 308 seats.

Quebec has often argued that its cultural survival within Canada would be compromised by a decline in political clout. Quebec sovereigntists have seized on the proposed seat changes, saying the 24 per cent level is a "bare minimum."

Normally, the seating in the House of Commons is adjusted after each census using a complex formula adopted in 1985, but the federal Conservatives have said that formula penalized some regions.

The legislation introduced last spring was to have updated the formula to make sure future readjustments help the faster-growing provinces.

Without changes to the House of Commons, it was estimated that many ridings in Ontario, Alberta and British Columbia would have well above the national average of voters.

Pure representation by population is considered almost impossible in Canada because there are guarantees in the system that say no province can have fewer MPs than it has senators. That means Prince Edward Island, with about 141,000 people, is assured of four MPs — or one for every 35,000 people.

If Ontario receives more seats in the Commons, McGuinty has said he would look at adding a similar number of seats to the provincial legislature to try to maintain the same riding boundaries.

Ontario generally mirrors federal ridings for its legislature, although the province maintained one additional northern riding that was wiped out by Ottawa in the last redistribution of Commons seats.

— With files from Joan Bryden in Ottawa.