Quebec's labour minister "won't back down" from plans to change rules governing construction unions in the province, despite being personally threatened and facing an illegal work stoppage Monday that paralyzed dozens of major building zones.

"Am I worried about my safety? Honestly, no," Labour Minister Lise Thériault told reporters Monday, after revealing she has received anonymous threats someone will "break both her legs" over the government's proposed Bill 33.

"Threats and intimidation have the opposite effect for me: I will not back down. We will abolish union placement."

The proposed Bill 33 would limit the power of construction unions.

Bill 33 Would force construction unions to make their finances public.

Would impose outside audits on construction unions.

Would limit union control over job placement.

Would allow contractors to staff their own jobs.

Construction workers struck back Monday, with crews marching off job sites across the province, bringing major sites such as the McGill University superhospital to a standstill.

Members of two union federations, the Fédération des travailleurs du Québec (FTQ) and the Conseil des métiers de la construction du Québec (CPMCQ) took part in the illegal work stoppage.

Some workers protested in front of the offices of Quebec's construction commission, where unidentified individuals smashed some windows.

Workers who walked off the job said their actions were not organized by their leaders — but rather a spontaneous gesture by frustrated workers, who indicated the action may continue all week.

Neither union involved has officially commented on the work stoppage Monday.

But the government blamed union leaders for bullying their members off their worksites, with Thériault warning that they face tens of thousands of dollars for each day of disruption.

Thériault urged unions to allow construction work to continue uninterrupted and to express any concerns about the legislation in committee hearings, due to start in Quebec City this week.

Bill 33 useless, says FTQ union federation

The Quebec Construction Commission also weighed in on Monday’s work stoppages.

Commission president Diane Lemieux asked union leaders "to take the actions they need to take to end this."

"This is 2011. There are other ways of doing things," she said.

Earlier this month, FTQ president Michel Arsenault called Bill 33 useless and a waste of money and argued that union officials can better assign workers to sites than bureaucrats can.

The Liberal government drafted Bill 33 as part of its efforts to curb the influence of organized crime in the construction sector.

Monday’s work stoppages appeared to ease traffic congestion in many parts of Montreal normally tied up by lane closures.

They also diverted media attention from the ongoing construction and corruption scandal that has dominated Quebec headlines for weeks.