Quebec's building authority, the Régie du bâtiment has temporarily suspended licenses for two major construction companies — Simard-Beaudry and Louisbourg.
The suspensions are the most severe sanction ever issued by the provincial authority.
They come more than a year after both Montreal-based companies pleaded guilty to tax evasion worth $4 million.
At that time the companies were ordered to pay a total of $8-million in fines and back taxes.
Simard-Beaudry's license is frozen from Feb. 1 to June 10, inclusively.
Louisbourg Construction's license is suspended from Feb. 1 to June 30.
Both companies are banned from bidding on public contracts for a period of four years.
That sanction was introduced in Quebec's recent anti-corruption law.
More than three quarters of work done by both companies has, until now been in the public sector.
Both companies currently oversee five different public works projects.
Work at those sites will be suspended Feb. 1.
Simard-Beaudry and Louisbourg have also been cited for breaking several workplace health and safety laws.