Another 55 people were still at large, officials said. None of the detainees had been charged with any crimes, the Canadian Broadcasting Corp. reported.
Immigration Minister Jason Kenney says the foreign nationals were brought from Romania via Mexico and the United States this year, entering Canada at Stanstead, Quebec, the CBC said.
"Unfortunately, there are criminal organizations that from time to time seek to abuse our immigration laws and profit from that abuse," he said.
The CBC said its sources said many or most of the detainees were members of the Roma ethnic group.
An unnamed government source told the news network the alleged smugglers would offer to get people into Canada by promising them good jobs. Once they arrived, they were told they owed large amounts of money to the traffickers. Some of the newcomers would allegedly resort to thievery to support themselves.
Most of them ended up in Toronto, with some moving to Winnipeg and Thunder Bay, Ontario, and Montreal, Kenney said.