A controversial former construction boss testified at the Charbonneau Commission that Boisclair authorized a $2.5-million subsidy in 2003 for a project involving a company that had ties to the Hells Angels.
Paul Sauve's testimony occurred last week but was under a publication ban until Tuesday afternoon.
On Wednesday, the Coalition's Jacques Duchesneau, a crusading anti-corruption investigator and police chief before he entered politics, drew links between the criminal organization and the fact Boisclair has admitted to using cocaine before.
Boisclair, who is currently Quebec's delegate-general in New York City, was municipal affairs minister in 2003 when the money was awarded shortly before a provincial election that saw the Liberals oust the PQ.
"I am making a link between the $2.5 million, someone associated with the Hells Angels, and someone who consumed (drugs) and made decisions," Duchesneau told reporters outside the legislature chamber, before making similar remarks in TV interviews.
"So that, and other questions too, will be asked at the opportune time.
"In 2005, Mr. Boisclair himself admitted that he used cocaine while he was a (cabinet) minister. So the question is: with Mr. Sauve being associated with the Hells Angels, and a subsidy of $2.5 million being granted, did that influence his (Boisclair's) decision? I don't know."
In a statement issued later Wednesday, Boisclair blasted Duchesneau and said a letter would be sent telling the former police chief he will face legal action unless he retracts his comments.
"His recent statements and the incorrect association that he has made about me are highly defamatory and harmful to my reputation," Boisclair said.
"And furthermore, they were issued with the intention of harming me."
Boisclair said he has known Sauve for years but that the money for the renovation of a Montreal church was awarded in good faith and that everything was above board.
Earlier, the PQ government brushed off a demand that Boisclair be removed from his job as Quebec's representative in New York.
The PQ was fuming over what it described as a defamatory smear job.
Boisclair's boss said he had spoken with him and had been assured the contract was awarded properly.
International Relations Minister Jean-Francois Lisee said Boisclair is willing to testify at the Charbonneau inquiry.
But what especially angered Lisee were the links Duchesneau drew between that contract and drug use.
He noted that Duchesneau has been described as Quebec's Eliot Ness. Lisee said he was acting more like Quebec's Joseph McCarthy, the anti-communist demagogue.
"He made crazy statements, without any proof, about a former member of this assembly," Lisee said of Duchesneau.
"He dishonours himself and undermines his own credibility."
He said Duchesneau should either offer proof of what he's insinuating or withdraw his remarks.
Boisclair was a cabinet minister until the PQ lost the 2003 election, then became party leader in 2005. He left politics after losing the 2007 election and was appointed to his diplomatic post last year.
Duchesneau worked for the government anti-collusion unit under the Charest Liberals and previously admitted leaking a devastating report to the media that pressured the government to call the Charbonneau inquiry.Suggest a correction