Canadian police and intelligence agencies will announce multiple arrests tonight after an operation to thwart a "major terrorist attack," the Canadian Broadcasting Corporation reported, citing unidentified "highly placed" sources.

The operation was coordinated with the U.S. Department of Homeland Security and the FBI, CBC said.

Canada's national police agency is expected to hold a news conference to give details of the alleged plot.

Law enforcement officials said the suspects have no connection to the two brothers accused of bombings at the Boston Marathon last week, CBC said.

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