TORONTO, June 3: Police have arrested 17 people, including five teenagers, on terror-related charges, a senior Royal Canadian Mounted Police officer told a televised news conference here on Saturday morning.

All the men arrested were residents of Canada and most were Canadian citizens, said Mike McDonell, the assistant commissioner of the RCMP.

He said they have been charged with a number of terrorism offences. Mr McDonell claimed that the arrested people were planning to commit a series of terror attacks against Canadian targets in southern Ontario.

He said that three tons of fertilizer ammonium nitrate were seized in relation to the alleged plot, three times as much as was used in the 1995 Oklahoma City bombing.

Replying to a question, he said the underground rail system was not the target, and declined to release the names of the arrested people. He also refused to give their background saying high-level investigations were going on.

“Six of the adults arrested are from Mississauga, two from Kingston and four from Toronto,” he said.

He said some of the arrested people were students, some employed and some not.

Reuters adds: “This group posed a real and serious threat,” Mr McDonnell said. “It had the capacity and intent to carry out attacks. Our investigation and arrests prevented the assembly of any bombs and the attacks being carried out. ... The modus operandi is very similar to other attacks that have taken place around the world and other threat of attacks.”

He said the investigation that led to the arrests had involved some 400 police and security experts, and had taken thousands of hours of painstaking detective work.

Police have charged them with terrorism-related offences. Officials said they had trained together in a camp in Canada.

“For various reasons, they appear to have become adherents of a violent ideology inspired by Al Qaeda,” said Luc Portelance, assistant director of operations at the Canadian spy service, the Canadian Security Intelligence Service (CSIS).

There have been no Al Qaeda-type attacks in Canada, although security services have long fretted about possible risks and the United States has urged more vigilance on the long border the two countries share.

AFP adds: The Toronto Star newspaper reported on its website that police swooped down on 12 locations in the Toronto area on Friday night to arrest members of a ‘home-grown terrorist cell’.

Citing unnamed sources, the newspaper said the CSIS had monitored the group since 2004 and the RCMP launched an investigation last year.

The accused were being held at a police station in Pickering, a suburb of Toronto, surrounded by heavily armed police, and were expected to appear in court later Saturday, officials said.

Prime Minister Stephen Harper was informed about the operation, his spokesperson said, but declined to comment on it immediately.

“The prime minister was briefed about the operation, but we do not want to comment because we do not want to derail the police operation,” spokesman Stephane Rondeau said.