Canadian police and intelligence agencies will announce later today they have thwarted a plot to carry out a major terrorist attack, arresting two suspects in Montreal and Toronto, CBC News has learned.

Highly placed sources tell CBC News the alleged plotters have been under surveillance for more than a year in Quebec and southern Ontario.

The two men are expected to appear in court tomorrow.

The investigation was part of a cross-border operation involving Canadian law enforcement agencies, the FBI and the U.S. Department of Homeland Security.

According to a Reuters report, U.S. law enforcement and national security sources said the alleged plot targeted a railroad between Toronto and New York City.


The arrests Monday morning were co-ordinated and executed by a special joint task force of RCMP and CSIS anti-terrorism units, combined with provincial and municipal police forces in Ontario and Quebec.

The RCMP are expected to hold a press conference Monday afternoon to announce the arrests and provide details of the alleged plot, and give an overview of the extensive police and intelligence operation.

Law enforcement officials say the terror suspects arrested today have no connection to the two brothers accused of last week's Boston Marathon bombings.

They also say there is no tie to the former London, Ont., high school friends who joined al-Qaeda and died earlier this year while helping to stage a bloody attack on an Algerian gas refinery.

Alleged plot recalls Toronto 18 case

Sources say the alleged plot disrupted by Monday's arrests was potentially more dangerous than the bombings and hostage-takings planned by the so-called Toronto 18.

Police have made a number of arrests in southern Ontario and Quebec following a joint operation between Canadian and U.S. authorities.Police have made a number of arrests in southern Ontario and Quebec following a joint operation between Canadian and U.S. authorities. (CBC)

That plot was broken up in the summer of 2006, when police arrested 18 people in a massive anti-terrorism sweep in southern Ontario.

Eleven of the 18 were subsequently convicted of aiding the group in various plots, ranging from blowing up the Peace Tower on Parliament Hill and the Toronto Stock Exchange with trucks laden with explosives to beheading the prime minister and other politicians.

The group never got a chance to execute any of its plans before being arrested when one of its members took delivery of what they thought were three tonnes of explosive fertilizer to be used in truck bombs. Undercover agents had replaced the shipment with harmless chemicals.

Four are serving sentences of 18 years to life in prison, while the other seven received terms ranging from 30 months to just over seven years.

More recently, three Canadian citizens were arrested in August, 2010 — two Ottawa men and a London, Ont. doctor — and charged with knowingly facilitating a terrorist activity.

One of them, Hiva Alizadeh, was also charged with possession of more than 50 circuit boards allegedly to be used as remote detonators for bombs.

The cases involving those three have yet to go to court.