MONTREAL -- Superior Court Justice France Charbonneau is scheduled to release her long-awaited report on corruption in Quebec's construction industry Tuesday, more than three years after the public inquiry she led began hearing its first witnesses.

Charbonneau will deliver a speech at 11 a.m., just as the report is released online.

The inquiry, known as the Charbonneau Commission, said in a statement Monday that Charbonneau will not take questions or give interviews.

Former Quebec premier Jean Charest created the commission in 2011 after months of intense public pressure, sparked in large part by a series of scandalous exposes by investigative journalists on the construction industry and its ties to organized crime and the financing of political parties.

The inquiry heard testimony over a 30-month span, beginning in the summer of 2012.

Bureaucrats, engineering and consulting executives as well as construction bosses talked about widespread collusion aimed at inflating the price of contracts for publicly funded infrastructure projects across the province.

Witnesses described how some construction companies had ties to organized crime and that the widespread collusion benefited political parties and corrupt bureaucrats.

One witness, ex-construction boss Lino Zambito, testified he was involved in a bid-rigging cartel and that the Mafia imposed a "tax" on certain public contracts.

The inquiry heard how reputed Mafia boss Vito Rizzuto, who died in December 2013, once helped decide who should win a certain bid for a road project in Quebec.

The allegations that surfaced at the commission forced then-Montreal mayor Gerald Tremblay to resign in shame in November 2012 after he was accused of being wilfully blind to the crooked bureaucrats and politicians in his inner circle.

Charbonneau's original deadline to produce a report was October 2013 but the former Parti Quebecois government extended it by 18 months in early in 2013 until April 2015.

Earlier this year, the current Liberal government extended the deadline until the end of this month.