Three men arrested in Canada on terror-related charges -- one of whom was reported to have once auditioned for the Canadian Idol TV show -- were plotting bomb attacks and had connections to a group fighting coalition forces in Afghanistan, police said on Thursday.

Police arrested two of the men in Ottawa on Wednesday and a third in London, Ontario, on Thursday, following a nearly year-long investigation. It was the country's biggest anti-terror sweep since a plan by the Toronto 18 conspirators to blow up Canadian landmarks was uncovered in 2006.

The lead investigator said police made the arrests this week because they believed some form of action was imminent.

This group posed a real and serious threat to the national capital region and Canada's national security, Serge Therriault, chief investigator for the Royal Canadian Mounted Police, told reporters.

Our criminal investigation and arrests prevented the assembly of any bombs and the terrorist attack or attacks from being carried out.

Because the case is now before the courts, police would not say how advanced they will allege the group's plans were.

Therriault said police made the arrests now because of the imminence of certain things and because they had gathered enough evidence to support the charges. During the past year there were varying degrees of imminence to the threat of an attack, he said.

Police alleged the group's targets were two-fold: Ottawa and NATO forces in Afghanistan, the latter through financing weapons purchases for groups fighting in that country.

Police said they found the suspects, all of whom are Canadian citizens, in possession of bomb-making instructions and more than 50 electronic circuit boards designed to remotely detonate improvised explosive devices.

They also found evidence suggesting one member of the group received outside training in building bombs, Therriault said.

The suspects were identified as Hiva Mohammad Alizadeh, 30, Misbahuddin Ahmed, 26, both of Ottawa, and Khurram Syed Sher, 28, of London, Ontario.

Alizadeh faces the most serious charges of possessing explosives and terrorist financing. All three are charged with conspiracy to commit terrorist acts with others in Canada, Iran, Afghanistan, Dubai and Pakistan.

Police named three other suspects in the case -- James Lara, Rizgar Alizadeh and Zakaria Mamosta -- but said they were not in Canada.

CANADIAN IDOL

Little is known about the suspects' personal lives at this stage.

The Toronto Star newspaper reported that Sher auditioned for the Canadian version of the American Idol reality TV show in 2008.

In a YouTube video of the episode, a man tells the judges that he arrived in Canada in 2005 from his native Pakistan before he performs a stilted rendition of the Avril Lavigne tune Complicated while dancing and moon-walking. The panel rejects him. http://www.youtube.com/watch?v=MHwTja3KBGo&feature=player_embedded

Therriault said he could not confirm any Canadian Idol connection.

The Globe and Mail newspaper reported that Ahmed was an X-ray technician and Sher a doctor.

Ahmed's lawyer, Ian Carter, said his client is married with a baby daughter and was shocked to be in detention.

He is shocked but relatively calm, holding up fairly well given the serious nature of the charges and the fact that he's a young father, Carter told the Canadian Broadcasting Corp.

Canadians may have been surprised to learn of the possibility of home-grown terror cells in their own backyard but the Conservative government of Prime Minister Stephen Harper has insisted the country is not immune to such threats.

Public Safety Minister Vic Toews declined to say if the alleged bomb plot could be connected to al Qaeda but said the group's presence in Canada is an ongoing concern.

There is undoubtedly an al Qaeda influence in some of the radicalization that is taking place, Toews told reporters in Winnipeg.

Ottawa's most recent brush with terrorism was the case of Momin Khawaja, who was caught building detonators in his basement in 2004.

Of the 18 men charged with terror-related crimes in the 2006 Toronto 18 case, police dropped charges for seven and 11 either pleaded guilty or were found guilty in court. Sentences so far have ranged from time served to life in prison.

(Reporting by Louise Egan, Jeffrey Jones and Rod Nickel; editing by Peter Galloway)