Investigators with the Quebec anti-corruption unit (UPAC) are raiding the offices of several construction firms north of Montreal this morning.

About 70 UPAC agents are carrying out the operation at the offices of Garnier Construction in Laval, the offices of Saramac in Terrebonne and Schokbeton in Saint-Eustache.

Sources told Radio-Canada, CBC's French-language service, that the raids are linked to illegal political financing connected to the Quebec Liberal party.

About a dozen people are expected to be questioned by investigators over the course of the day.