Speaking at a press conference Sunday afternoon, Blanchet said the allegation “goes completely against everything I am.”
“I have never acted the way that has been alleged, I have never done what was described in the Facebook post,” he said.
Blanchet said the allegations were “political” and “militant” and that he is the victim of libel.
“Imagine for just one moment the hell in which these people, these anonymous people have thrown you into,” he said. “It makes your blood run cold.”
In a statement released earlier on Sunday, the Bloc Quebecois caucus said Blanchet is a man of “integrity,” and is “honest and determined to serve the interest of Quebecers.”
“We are convinced that the anonymous allegations made against him are false and we support him without hesitation,” the statement reads in French.
The party said it is a “staunch defender of the legal society,” and has worked to “improve the living conditions of women and men in Quebec.”
“This is what we were elected for and what we will continue to do with our leader, Yves-François Blanchet,” the statement said.
The allegations were posted anonymously on July 14 to a Facebook page called “Hyènes en jupons” — or “Hyenas in skirts.” The group describes itself as a feminist collective that aims for change through disruption.
Global News does not know the identity of the accuser and has not been able to verify the claims in the post.
The post claims Blanchet tried to force himself on a woman in the washroom of a Montreal bar in 1999.
The post claims the alleged incident took place after a party celebrating the release of Canadian singer Isabelle Boulay’s album.
Asked by reporters if he was, in fact, at the album launch event, Blanchet said it is possible, but that the rest of the Facebook post is untrue.
“Is it likely that I was with Eric Lapointe that night for the launch of an album of Isabelle Boulay – yes,” he said. “But the rest is pure fantasy and I am denying the allegations as described at this point.”
Blanchet said he would like an investigation into the Facebook post which he said is “defamatory,” and that the post must be withdrawn.
Blanchet has been the leader of the Bloc Quebecois since January of last year.
Asked if he should step down as party leader, Blanchet said doing so over “anonymous allegations” would be “unimaginable.”
“So my answer is very clear,” he said. “I am going to continue as leader of the Bloc and the caucus has unanimously supported this position.”
–With files from Global News’ Beatrice Britneff and The Canadian Press