At least some of that information came from the U.S. Federal Bureau of Investigation and the London Metropolitan Police, says an affidavit filed by the RCMP in the Federal Court of Canada.
Other material was apparently gleaned through the secretive "Five Eyes" eavesdropping network.
The records shed new light on the investigation that led to the high-profile 2010 arrests of Misbahuddin Ahmed and Hiva Mohammad Alizadeh of Ottawa, and Khurram Syed Sher, of London, Ont.
The Federal Court is slated to hold hearings next week on a government application to keep certain classified information under wraps during the criminal trials for the three men, which are still several months away.
Following the sensational arrests in August 2010, police said they seized terrorist literature, videos and manuals, along with dozens of electronic circuit boards allegedly designed to detonate homemade bombs remotely.
Ahmed, 29, worked as an X-ray technician at an Ottawa hospital, while Alizadeh, 33, had studied electrical engineering technology at Red River College in Winnipeg. Sher, a 31-year-old doctor of pathology, once danced and sang on the Canadian Idol TV program.
They are charged with various Anti-Terrorism Act offences.
The federal government has applied under the Canada Evidence Act to maintain a cloak of secrecy over portions of the approximately 9,300 documents disclosed to defence counsel in the criminal cases.
The government argues the sections must remain blacked out to prevent disclosure of information that would be "injurious to national security, international relations or national defence."
Court filings related to the federal request provide fresh glimpses of the terrorism case that has largely unfolded quietly behind the scenes since sparking banner headlines in the summer of 2010.
A heavily edited court transcript of a closed-door proceeding last Dec. 6 about the federal request for redactions indicates the Canadian Security Intelligence Service relied on an undercover source during the terrorism investigation.
"In fact, in this particular case, the information about the CSIS human source is contained in a number of affidavits for search warrants and wiretaps and so on," Andre Seguin, a lawyer with the Justice Department's national security group, says at one point.
Seguin notes that although the information has been disclosed to defence counsel, it remains sealed and cannot be seen by the public.
Seguin did not return a phone call seeking elaboration.
In an affidavit filed in the Federal Court proceeding, CSIS official Bradley Evans says the spy service supports the federal request to keep certain information secret, saying that, if disclosed, it "could lead to the identification of a human source."
Other information at issue could identify CSIS's interest in particular groups or individuals, investigative techniques, relationships with other security agencies, and the names of CSIS employees, Evans says.
In his affidavit, Capt. Maitland Barber, a senior intelligence official with the Canadian Forces, stresses the importance of safeguarding information provided by Canada's allies in the "Five Eyes" intelligence community — the United States, Britain, Australia and New Zealand.
Barber reveals that two of those key allies provided the Canadian Forces with material relevant to the terrorism case.
"It is my understanding that a portion of information being protected from disclosure was originated by the United States," says Barber's affidavit.
"It is also my understanding that a portion of the information being protected from disclosure was originated by the United Kingdom."
Intelligence produced and collected in concert with these allies has generally "proven invaluable," he adds. "Damaging trust and respect through the disclosure of information against the express wishes of one or more of these Allies would have a detrimental effect on our future collaborative efforts."
RCMP Insp. Patrick Watts says in an affidavit he has been advised that information related to the terrorism case that the Mounties wish to protect "comes from foreign law enforcement and intelligence agencies and that most of it is from the U.S. Federal Bureau of Investigation (FBI) or the U.K. London Metropolitan Police."
Watts says the RCMP consulted its foreign partners about their willingness to disclose the classified information, and that the material they were willing to disclose has already been given to defence lawyers.
As for the remaining information, Watts says it is important to shield it in order to preserve relations with foreign agencies.
"The RCMP currently has a number of ongoing investigations and open files in which it is receiving information from American and British agencies," says his affidavit. "The RCMP's relationship with these agencies is critical to its ability to carry out these national security investigations, and future ones."
The Federal Court has set aside four days next week to consider the federal request to keep material secret. Given the nature of the proceedings, some sessions will include only the judge, federal lawyers and an amicus curiae — a specially appointed, security cleared lawyer who will serve as a check against federal demands.
Matt Webber, lawyer for Alizadeh, noted the Canada Evidence Act process is supposed to yield a balance between the security interests of the state and the right of the accused to a fair trial.
"Right now, I'm optimistic that the judge and the amicus will get anything relevant and important into my hands," Webber said. "We'll just have to wait and see how it plays out."
Alizadeh and Ahmed are slated to go to trial in Ontario court next April, while Sher is to be tried separately beginning in February.
Three other men, all believed to be living abroad, have been named as unindicted co-conspirators.
Police claim the alleged plot stretches from Ottawa to Afghanistan, Dubai, Iran and Pakistan. But there has been no official word on the purported targets — or even if things had advanced to the stage of a planned attack.
Authorities said they made arrests when they did to prevent the suspects from sending money to counterparts to buy weapons that would be used against coalition forces in Afghanistan.