Provincial police moved in to grab documents at the Canadian Malartic mine, which belongs to Montreal-based Osisko Mining Corp. (TSX:OSK)
They were joining representatives of the provincial Environment ministry.
A spokeswoman for Environment Minister Daniel Breton said the raid was prompted by allegations that the company broke the conditions of the deal that allowed it to exploit the mine.
She said departmental officials demanded documents linked to drilling and blasting from April 2011 to October 2012.
The western Quebec site has been the largest gold mine in Canada, although it's set to be overtaken soon by the Detour Lake mine in Ontario.