RCMP officers raided the offices of a major Quebec construction company on Tuesday as part of a corruption investigation that has led to the arrests of two Canada Revenue Agency officials.

One of the officials works for a branch of the federal agency that deals with black-market activities, and the other works for a branch that does tax-avoidance probes, the Globe and Mail reported. So far, no charges have been laid.

The corruption scheme is alleged to have involved at least one employee who gave favourable treatment to certain companies, reported the CBC's French-language service, Radio-Canada.

The Canada Revenue Agency said it will hold a news conference Wednesday to provide more details on the investigation.

RCMP and Canada Revenue Agency officials raided the offices of Montreal-based Simard-Beaudry Construction Inc., the largest firm in the business empire of magnate Tony Accurso.

Accurso has made headlines in recent weeks over revelations that he hosted a high-ranking Montreal politician and union officials on his yacht while his company was bidding on city contracts.

Simard-Beaudry won a $355-million contract in late 2007 from the City of Montreal to install and oversee water meters. Last week, it was reported that former Montreal councillor and city executive committee chairman Frank Zampino stayed on Accurso's yacht while the contract was out for tender.

Other guests on Accurso's yacht have included Quebec Labour Federation president Michel Arsenault, whose umbrella group represents the largest construction union in the province, and Jean Lavallée, a former federation executive. All three spent a week in the Bahamas on the luxury vessel in December.

Accurso's companies have benefited from $250 million in investments from the labour federation's investment fund over the last 20 years, according to financial records. One of his construction firms also built the labour federation's Montreal headquarters.

Quebec Transport Minister Julie Boulet said Tuesday she hadn't heard anything about the search at Simard-Beaudry's offices. Amid the rampant allegations of misdealing in the province's construction industry, Boulet affirmed that her ministry follows strict rules in awarding contracts.