Three Canadians arrested in an alleged terrorist conspiracy had bomb parts and plans and posed a "real and serious threat", according to police.
The trio, arrested this week, were charged with supporting terrorism.
Hiva Alizadeh and Misbahuddin Ahmed were jailed following a court appearance on Thursday. Also arrested was Khurram Sher, the BBC reports.
Police said Mr Alizadeh, 30, Mr Ahmed, 26, and Mr Sher, 28, face charges of conspiracy to facilitate terrorism, with Mr Alizadeh also charged with providing or making property available for a terrorist organisation and possession of explosives.
Mr Alizadeh and Mr Ahmed are residents of Ottawa, and Mr Sher is a resident of London in Ontario.
The lead investigator in the case, Royal Canadian Mounted Police Chief Superintendent Serge Therriault, said police had arrested the suspects this week because they believed an attack was imminent.
Mr Therriault said the group had sought to support anti-coalition fighters in Afghanistan. It was unclear whether the group planned attacks in Canada.
Police said investigators had seized bomb-making instructions and more than 50 circuit boards specifically designed to remotely detonate bombs.