The province of Saskatchewan has asked the Canadian government to block a hostile bid by BHP Billiton for Potash Corporation.
The province is home to the fertiliser group.
Premier Brad Wall said the takeover was not in the interests of Saskatchewan or of Canada.
The BBC reports the Canadian government must now decide whether to block the deal.
Last month, Potash asked a court in the United States to block the bid. BHP said the lawsuit in a district court in Chicago was "entirely without merit".
The Anglo-Australian mining group offered $US39 billion (£25bn) for the company in August.
the BBC reports potash is used for fertiliser production worldwide.