Jacques Duchesneau, a former city police chief and civil servant who testified recently at the province's corruption inquiry, made the remarks in an interview published Wednesday in the Montreal Gazette.
The men have been feuding in the wake of Duchesneau's testimony at the inquiry, where he said he tried talking to the mayor in 2009 about corruption at city hall.
Mayor Tremblay has denied having discussed that topic with him. He's now calling the latest remarks from Duchesneau unacceptable and won't say whether he might sue over them.
Duchesneau is quoted telling the newspaper: "Would you buy a used bicycle from this guy?... I wouldn't. He can say whatever he wants... He says he doesn't remember anything but he remembers that we didn't talk about it. He can go to hell as far as I'm concerned. You call him a mayor?"
The origins of the rivalry run deep, even before the inquiry. Duchesneau, in fact, was a political opponent who once ran for mayor.
Tremblay is now challenging Duchesneau to back up the explosive claims he made while testifying at the inquiry earlier this month. Duchesneau testified that 70 per cent of the money raised by Quebec political parties is collected illegally.
The mayor wants specifics — names and details.
"If it's true, as he says, that he informed me, warned me, and identified certain people in my entourage, I reiterate that he has a duty to reveal these names immediately. It's in everyone's interest. It's also what he should have done while under immunity at the Charbonneau (inquiry)," Tremblay said in a statement.
"Like Mr. Duchesneau, I deeply hope that all light might be shed on corruption and collusion. But it's not by lowering ourselves to personal insults that we'll get ahead."
Duchesneau told the Gazette that there will, indeed, be plenty of new details.
He says his own claims came from testimony he gathered and that one of his informants — a "big guy" political fundraiser — is set to share details when the inquiry resumes this fall. He says the informant was so distressed that he contacted Duchesneau, but not before confessing to a priest.
Duchesneau says that since appearing at the inquiry he's received at least 278 emails, including tips, from the general public.
He also told the newspaper that he'll need to lay low for a while, for security reasons. He hinted that he has received threats and that his family is scared.