OTTAWA - The Conservative government was shaken to its core by the sudden resignation of Foreign Affairs Minister Maxime Bernier over a security breach involving secret documents carelessly left at his ex-girlfriend's home.

Prime Minister Stephen Harper told an extraordinary evening news conference Monday that Bernier's controversial relationship with a woman linked to the Hells Angels was not a factor in the decision.

He said it was prompted by an error involving classified documents and sources say they included briefing material for his trip to the NATO summit where Canada announced it would remain in Afghanistan.

"This is about one thing and that is a failure to uphold expected standards on government documents," Harper said in the Commons foyer.

"It is a very serious mistake - regardless of who the minister is, regardless of personal life - to leave classified documents in an unsecured location."

The resignation announcement came a scant two hours before Julie Couillard was broadcast on a French-language television network

A source told The Canadian Press that the package included a mix of classified material and other briefing notes publicly available through the Access to Information Act.

The package, he said, was preparation material for Bernier's trip to the NATO summit in Bucharest - where Canada announced the extension of its military mission in Afghanistan until 2011.

Just hours before the axe fell on Bernier, the prime minister had dismissed the whole affair.

"I have no intention to comment on a minister's former girlfriend," the prime minister said to wrap up a news conference earlier Monday with visiting Ukrainian President Victor Yushchenko. "I don't take this subject seriously."

He's taking it seriously now.

The prime minister has lost a minister once described as a rising star who was once touted as a future leader. Bernier was exceedingly popular in Quebec and he romped easily to victory in Beauce.

Bernier's departure makes it a near certainty that the prime minister will have to shuffle his cabinet.

Harper announced that the foreign affairs portfolio will be handled on an interim basis by David Emerson - the ex-Liberal and current Conservative trade minister. He dropped the bombshell before leaving the country late Monday night on a European diplomatic trip.

Opposition MPs were baying for further details that could prove extremely embarrassing for the Conservative government.

Liberal MP Ralph Goodale said Harper has been "very dismissive" of the Bernier-Couillard affair for weeks.

"That raises some questions about his judgment," Goodale said of the prime minister.

Bernier has been under fire for a series of gaffes in his role as Canada's top diplomat, and the revelation that his girlfriend of the past year had once been romantically linked to several men with links to the Hells Angels had security experts - and political opponents - asking whether she had undergone a security check.

The question remains unanswered.

NDP Leader Jack Layton said the latest revelation was "the straw that broke the camel's back" for Bernier's cabinet career.

It was with great fanfare that Bernier was sworn in last summer to a cabinet portfolio once held by Lester Pearson, Joe Clark and Jean Chretien. Accompanying him to the traditional ceremony was his new girlfriend, Couillard, and images of the photogenic couple were splashed across the nation's newspapers.

But when he was moved from an economic portfolio at Industry to a post that required diplomatic finesse and a grasp of global issues, Bernier's gaffes began piling up.

Bernier met the Haitian president and then got his name wrong. He helped quash efforts to replace the governor of Kandahar by publicly disclosing those efforts. He promised aid for Burma on a plane that wasn't available.

Other ministers were sometimes asked to speak on sensitive foreign-affairs issues while the minister was sidelined.

A Conservative staffer recently said there were concerns immediately after the House of Commons returned from the 2007 summer recess that he was in over his head.

But the prime minister always defended him with vigour - and came to his defence several times as stories about his relationship with Couillard began raising eyebrows.

As late as Monday afternoon, he was brushing aside the latest twist in the Couillard saga.

Federal records show that a security firm linked to Couillard bid for two federal airport contracts - one to monitor the activity of screening personnel, and another to install software at walk-through metal detectors.

That Bernier's ex-girlfriend was married to one biker and lived with another tied to the Hells Angels has been known for weeks.

It had since been reported that a more recent boyfriend who ran a security firm committed suicide while he owed money to the Hells Angels.

The government has said Couillard carried no security risk, but it has steadfastly refused to say whether security checks were ever even conducted.

In his first Parliament Hill press conference in months, the question was put to Harper and he blew it off.

"I have no intention to comment on a minister's former girlfriend," the prime minister said to wrap up a news conference with visiting Ukrainian President Victor Yushchenko. "I don't take this subject seriously."

Harper then spun on his heels and exited the room with his guest.

A spokesman at CATSA said there was no record of any contract bid by the Montreal-area security firm reportedly owned by Couillard, Itek Global Solutions.

But she reportedly played an active role in her late ex-boyfriend's company - D.R.P. Investigation and Security Agency - which bid unsuccessfully on two airport contracts.

CATSA spokesman Mathieu Larocque confirmed that the company would have had access to federal documents with basic information about airport security.

He said that kind of information would have been provided to all contract bidders, and to members of the public who filed an Access to Information request.

"They're not security sensitive," Larocque said of the documents.

He said D.R.P. bid unsuccessfully on a pair of contracts in December 2004 and February 2005 to install airport software.

One would have helped monitor the activity of screening personnel at locations across Canada, and recorded the time spent by employees at those various locations.

It also bid to install equipment at walk-through metal detectors that would gather data on passenger traffic at various times of the day.

The opposition said there's no reason to suspect Couillard - who has never been charged with a crime - of any wrongdoing.

But they said they have a right to ask questions about ties between a drug-dealing criminal network, firms with an interest in airport security, a minister's ex-girlfriend, and the Canadian government.

They reacted indignantly to the suggestion that they're gossip-mongering about Bernier's love life.

"The prime minister says he is not taking it seriously. Well, I'm starting to have difficulty taking the prime minister seriously," said Liberal MP Michael Ignatieff.

"I don't care about (Couillard's) skirts, I don't care about her cleavage, I don't care about her past. I don't care about any of it, it is none of my business quite rightly - but this stuff is not only my business, it is the business of all Canadians."
Couillard did not respond to an interview request. She says her name has been unfairly dragged through the mud and that the public humiliation has been devastating.