MONTREAL -- Quebec's revenue agency is searching offices linked to construction magnate Tony Accurso.

Investigators are exercising warrants this morning in the Montreal region at companies owned by Accurso -- as well as an accounting firm and an insurance company connected to the businessman.

A source tells The Canadian Press that this morning's searches are linked to Accurso -- even though Quebec's tax agency is refusing to confirm it.

Accurso -- a key figure in Quebec's ethics scandals -- was arrested twice in recent months and faces several charges including fraud, breach of trust, and bribery.

His name also surfaced this week in explosive testimony during Quebec's inquiry into corruption in the construction industry.

Accurso has vigorously denied testimony that he invited Mafia boss Vito Rizzuto to settle a dispute with another construction boss when that rival wanted to compete with him for a public contract.

Some 90 investigators are involved in this morning's operation to seize documents at these offices.