The Liberals are increasing pressure on the Conservatives for an investigation into the Maxime Bernier affair, after a Quebec advisor for the Tories resigned because of his connection to Bernier's ex-girlfriend Julie Couillard.

Bernard Cote, an adviser to Public Works Minister Michael Fortier, briefly dated Couillard while she tried to win a government contract. Couillard has also been involved with men who were either members of outlaw biker gangs or who had close ties to that world.

"There is the possibility that organized crime is trying to infiltrate the government," Liberal Leader Stephane Dion said Wednesday.

"I'm not saying it's what happened. But certainly all the experts of security who have spoken (say) ... this is the pattern that you need to check."

Cote was fired by the Conservatives on Tuesday after it was revealed he dated Couillard in 2007, while she was vying for at least one multi-million dollar contract for property developer Groupe Kevlar Inc. The company is expected to speak to reporters about the matter on Thursday.

Fortier said Public Works was handling the contract, so there was a conflict of interest for Cote.

"He should have actually recused himself from this matter, which he didn't do, hence his resignation," said Fortier.

Cote, a former real estate broker and property manager, ran unsuccessfully for the Progressive Conservatives on two previous occasions.

He marks the second Conservative casualty from dealings with Couillard. Bernier resigned as foreign affairs minister on May 26, hours before Couillard revealed he had left classified briefing materials in her apartment in mid-April.

"I think what we have to do here is ask for an independent inquiry," Liberal MP Mark Holland told CTV's Mike Duffy Live. "This just keeps getting more and more muddled, more and more tangled."

He added that it was important to investigate whether Prime Minister Stephen Harper knew about Couillard's past before the scandals broke. But Conservative MP Jason Kenney said it was ridiculous Harper would have known who his cabinet ministers were dating.

"I find it kind of humorous that the Opposition characterizes Stephen Harper as this all-knowing guy with his fingers into everything, and they criticize him for that," he said. "And now he's supposed to be keeping a registry of who's dating whom in the Conservative party and staffers?"

Commons hearings

On Tuesday, a House of Commons public safety committee heard that the RCMP was aware of Couillard before the scandal erupted over her relationship with Bernier.

Raf Souccar, the RCMP's assistant commissioner for federal and international operations, appeared before the committee examining the affair.

He did not specify what the RCMP knew about Couillard, or whether any information had been passed on to the government.

The committee is trying to determine the extent of the security breach. Bernier and Prime Minister Stephen Harper said they will not participate, although Couillard is expected to make an appearance next week.