Rio Tinto’s bid to complete a takeover of Turquoise Hill Resources has received a boost after the most vocal opponents of the deal agreed not to vote at the shareholder meeting that will determine whether the $US3.3 billion deal goes ahead.

Rio has owned almost 51 per cent of Canadian listed Turquoise Hill for a decade but this year moved to acquire the remaining 49 per cent as part of efforts to simplify the ownership structure of Mongolia’s Oyu Tolgoi copper mine.