Global miner Rio Tinto is clear to take over the Oyutolgoi project, which promises to be one of the world’s largest copper-gold mines, after project owner Ivanhoe Mines decided to scrap a controversial “poison pill” that would have allowed it to block Rio Tinto from raising its stake in Ivanhoe. An agreement capping Rio Tinto’s holding at 49 percent expired on Wednesday.

Rio Tinto, which has built its stake in Ivanhoe to 49 per cent as it has helped fund construction of Oyutolgoi, welcomed the decision.

“As the 49 percent cap on Rio Tinto”s ownership of Ivanhoe expires today, we are free to increase our shareholding as we see fit,” a Rio Tinto spokesman said on Wednesday.

In a statement, Ivanhoe said Rio Tinto recently told Ivanhoe’s board that it intends to buy additional shares to raise its stake to more than 50 per cent.

Ivanhoe’s rights plan, backed by shareholders in 2010 and due to expire next year, was dealt a fatal blow in December when a court ruled it could not be used to dilute Rio’s stake.