Rio Tinto’s bid to complete a takeover of Turquoise Hill Resources has hit another snag with a Canadian regulator opting to take a closer look at a deal done with the most vocal of the dissenting shareholders.

The intervention of the body responsible for financial regulation in Quebec has forced the postponement of a shareholder vote to decide the fate of the $US3.3 billion ($5.1 billion) deal aimed at simplifying the ownership structure of Mongolia’s Oyu Tolgoi copper mine.