About 400 regional police and federal agents were involved in the arrests Friday and early Saturday.
The Toronto Star reported Saturday that the men had trained at a camp north of Toronto and had plotted to attack the Canadian spy agency's downtown Toronto office, among other targets in Ontario province. Authorities refused to confirm those reports, but did say that contrary to other reports, Toronto's subway system did not appear to be a target.
The 12 adults, who range in age from 19 to 43, live in either Toronto, Canada's financial capital and largest city, or the nearby cities of Mississauga or Kingston.
Rocco Galati, a lawyer for two suspects from Mississauga, said Ahmad Ghany, 21, is a health sciences graduate from McMaster University in Hamilton. He was born in Canada, the son of a medical doctor who emigrated from Trinidad and Tobago.
Shareef Abdelhaleen, 30, is an unmarried computer programmer of Egyptian descent, Galati said. He emigrated from Egypt at the age of 10 with his father who is now an engineer on contract with Atomic Energy of Canada Ltd., the lawyer said. Atomic Energy of Canada provides services to nuclear utilities in Canada and other countries, according to its Web site.
The charges were filed under Canada's Anti-Terrorism Act, which was passed following the Sept. 11 attacks in the U.S., particularly after bin Laden named Canada as one of five so-called Christian nations that should be targeted for terror strikes.
Portelance said it was the largest counterterrorism operation in Canada since the adoption of the act and said more arrests were possible.
Associated Press reporter Rob Gillies in Toronto contributed to this report.