Terrorism suspect Najibullah Zazi travelled to Canada on at least one occasion, according to published reports, including a visit to his grandmother in Ontario.

Zazi's aunt, Maimoona Zazi, told the Globe and Mail that "it's the same guy" after seeing footage of her nephew on television.

According to his aunt, Zazi travelled to Canada "a year or two ago" to visit his grandmother in Mississauga for a few days.

Zazi told the newspaper that her nephew is not a terrorist. "He's a very good Muslim...a very nice boy," she said.

CTV News spoke with a teen who said he is Zazi's cousin, who insisted the accused is not a terrorist.

"Why is he being accused and all that?" said Yunis Zazi. "The fact that he's being accused is unbearable."

The revelations come after U.S. authorities told a Denver court Friday that they were investigating reports that Zazi made several trips north of the border, where he may have tried to organize a terror cell in Canada.

CSIS and RCMP officials refused to comment on Zazi's reported travels in Canada.

"It's going to take some serious checking in Canada to find out when he was there, why he was there, where he went, who he got in touch with and what his purpose was," said CTV's Paul Workman in Washington.

"The word 'several' is important in this because it shows that he travelled into the country on a number of occasions, and that's going to be very worrying both to the authorities in Canada and in the United States," Workman said.

At the G20 summit in Pittsburgh, Prime Minister Stephen Harper told a news conference that he can't discuss individual national security files.

However, "Canada monitors national security threats very carefully and we work hand-in-glove with our allies, in particular our American neighbours, on national security threats that cross our borders," he said.

Zazi returned to New York

On Friday, a U.S. federal marshall's aircraft flew Zazi to New York, where he will face charges of conspiracy to use weapons of mass destruction.

U.S. prosecutor Tim Neff told a federal judge that Zazi was in the middle of making a bomb when he was apprehended by U.S. authorities.

U.S. authorities allege they found handwritten bomb-making instructions on Zazi's computer, and they believe three accomplices helped him buy bomb-making items and may be at large.

Zazi's indictment stipulates that he was trained to make explosives in Pakistan by members of al Qaeda. Surveillance video shows a man appearing to be Zazi purchasing a large amount of hydrogen peroxide and nail-polish remover at beauty-supply stores, allegedly to make bombs.

Prosecutors have alleged that the bombs were to be detonated on New York City commuter trains on the anniversary of the September 11, 2001 attacks.

Transit warnings

Former CSIS agent Michel Juneau-Katsuya told CTV News Channel that Canadian transit authorities need to consider a warning program for commuters. Citing the London and Madrid bombings, he said transit systems are often targets for terror attacks.

"We don't have to wait until something happens. A terrorist threat is omnipresent," Juneau-Katsuya said.

"We've got to sort of raise the alertness, and I don't think we are doing it sufficiently.'

Defence lawyer Arthur Folsom told The Associated Press on Friday that his client maintains "that he was not part of a terrorist cell." Folsom added that federal agents found no trace of explosives in Zazi's car or apartment.

With files from the Associated Press