TORONTO

RCMP officials say they foiled what could have been a murderous terror attack on Canadian soil with links to al-Qaida.

Shortly after noon Monday, RCMP officers executed a series of search warrants in Toronto and Montreal and arrested Raed Jaser, 35, of Toronto and Chiheb Esseghaier, 30, of Montreal, who is of Tunisian nationality.

The pair were accused of planning to bomb a VIA passenger train in the GTA. Dubbed "Project SMOOTH" by police, three high-ranking RCMP officers offered few details about the plot at a press conference just hours after the raids.

"If that plot had been carried out, it would have resulted in innocent people being killed or seriously injured," said Assistant RCMP Commissioner James Malizia.

He said the men, who are not Canadian citizens, were allegedly communicating with al-Qaida operatives in Iran, planning the attack.

"The support being received was in the form of direction and guidance," Malizia said, adding there is no evidence the plot was state-sponsored.

Police said the plot was not connected to last Monday's deadly attack on the Boston Marathon.

They did not say if other suspects were being sought in connection with the terror plot.

Around a dozen law enforcement agencies, including the FBI in the United States, were involved in the investigation which started in August 2012. The suspects were allegedly observed watching trains in the GTA, said RCMP Chief Supt. Jennifer Strachan.

"It was definitely in the planning stage, but not imminent," she said, of the timing of the potential attack.

Sources have told the Toronto Sun one of the possible scenarios of the attack centred around blowing up a rail connection between New York and Ontario, near Niagara Falls.

"The plan was to take out a train with passengers on board and the crossing trestle," a police source said. "It was meant to be spectacular and there would have been a lot of carnage."

But Niagara Regional Police Chief Jeff McGuire said he had not received any information pointing to an attack in Niagara.

"I have been briefed on this investigation since I took over as chief," he said. "I have not received any information that there was a plan to use explosives to blow up the bridge over the Niagara River. The attack was focused on a train with intention to harm and kill members of the public."

Few details were available about the men Monday, but a spokesman for the Institut National de la Recherche Scientifique, near Montreal, confirmed that Esseghaier was a doctoral student at the research institute and that he had been arrested.

Julie Martineau, the school's director of communications, said Esseghaier arrived at the school in 2010 and was about half way through his degree.

"He is doing a PhD in the field of energy and materials sciences," she told Reuters.

A number of Muslim leaders were in attendance at the press conference. Tips from Toronto's Muslim community brought the suspects to police attention, confirmed RCMP Supt. Doug Best.

"Obviously, there was some community involvement to get as far as we've gotten," he said. "The community has been supportive."

Both VIA Rail and Amtrak released statements to the media following the arrests. VIA officials praised police and said there was no imminent threat to passengers or its employees.

"We cooperate with all involved in ensuring the safety and security of our passengers, our employees and the public. We do not comment on law enforcement activities."

Police said earlier this year that Canadians took part in an attack by militants on a gas plant in Algeria in January, while Canadian and Somalian authorities are investigating whether a former University of Toronto student participated in a bomb attack on Mogadishu last week.

And in 2006, police arrested and charged 18 Toronto-area men who were accused of planning to plant bombs at various Canadian targets. Eleven were eventually convicted.

In the most recent case, bail hearings are scheduled for Tuesday morning in Toronto.

-- With files from Reuters