MONTREAL - Two major Quebec construction firms linked to Tony Accurso have pleaded guilty to tax evasion.

The Canada Revenue Agency claims Louisbourg Construction Ltd. and Simard Beaudry Construction Inc. evaded $4.1 million in tax by claiming ineligible expenses.

Both firms avoided trial Tuesday by pleading guilty in a Laval courtroom. The companies will be forced to pay the government $8.2 million.

"We rarely see investigations of that magnitude," said prosecutor Francois Lanthier.

Louisbourg Construction was accused of claiming $15.3 million in non-deductible expenses from 2003 to 2008, and Simard Beaudry Construction was accused of claiming $3.5 million from 2005 to 2008.

"We've already paid the back taxes, and our goal is to fully cooperate," said Jean Groleau, attorney for Louisbourg and Simard-Beaudry.

According to provincial records, Accurso is the majority shareholder in Simard Beaudry and holds a minority interest in Louisbourg.

Accurso stirred controversy for inviting politicians and union leaders aboard his luxury yacht. Some of the invoices were found to be from work performed on the vessel.

Accurso's companies are responsible for major road construction projects for the provincial government, as well as in major cities like Montreal and Laval.

The tax evasion conviction could cost them their licences.

"The Regie du batiments (the government agency that applies the province's building code) has to do an inquiry, and after they decide what kind of sanction they have," said Labour Minister Lise Thibeault Tuesday.

The conviction echoed to question period at the National Assembly Tuesday, because Accurso and his companies have often been criticized for their close ties to the Liberal Party.

Earlier this year, Simard-Beaudry was awarded a major chunk of the McGill superhospital construction contract.

"Did you give Simard-Beaudry its biggest contract knowing it was under investigation?" asked Parti Quebecois House Leader Stephane Bedard.

Finance Minister Raymond Bachand denied any knowledge of the investigation.

"Investigations aren't leaked," he said.

With files from The Canadian Press