TORONTO - The Canadian government is making preparations for the arrival of Syrian refugees, including the possible construction of camps to house them, a government spokesman said on Thursday.

The spokesman confirmed the plans after the government issued a tender notice on Thursday seeking companies to build "temporary winterized lodgings for groups of 500 to 3,000 people by early December 2015 at sites to be confirmed."

Canada's army is also planning to winterize buildings normally used to house cadets during summer training in order to use them as temporary lodging for refugees, the Canadian Broadcasting Corporation (CBC) reported.

"The Canadian Armed Forces is currently planning on providing interim lodging at bases in Quebec and Ontario as a priority," Dominique Tessier, a media relations officer with the Department of National Defence, told the CBC in an email. "Other bases and locations may be used if requested by government of Canada planners."

There are no refugee camps in Canada. Immigration detention centers, similar to jails, are used during deportation, to guard against flight risk, or for temporary use by border agents during legal procedures. Refugees otherwise have freedom of movement.

Canada is planning for the arrival of 25,000 Syrian refugees before year end.

The notice from Public Works Canada said the housing and services may be required for up to three months and that the sites must be self-contained and self-sustaining, including on-site energy, water, sewage and waste management.

One U.S. official said his understanding was that once the refugees arrived in Canada, authorities would detain them in some kind of "camp" and not release them until after a thorough vetting.

Another U.S. security official said that as far as he knew, Canada and the United States were still using identical vetting procedures for Syrian refugees, which normally take 18 to 24 months.

Canada has said most of the security vetting for the refugees will be done before the refugees arrive. But to meet Prime Minister Justin Trudeau's Jan 1. deadline, some screening will have to be done after their arrival in Canada.

After last week's Paris attacks, the plan faces growing resistance from some provincial and municipal leaders who say the timeline does not allow for sufficient security checks.

At least six Canadian companies expressed interest in the tender notice. One of them, Sockeye Operations, said it could set up a temporary camp for hundreds of people within days, provided the government has sufficient space available.

Mike Naylor, vice president of operations at Sockeye, which builds temporary camps for oil-field workers in Alberta, said he did not expect the camps would hold thousands in a single location.

"To set up 3,000 beds in a week in one location would be pretty chaotic," Naylor told Reuters. "I'd be surprised if they went to camps that big in one location, but they might."