March 1 (Bloomberg) -- Rio Tinto Group, the world’s third- largest mining company, will spend C$245 million ($233 million) to increase its holding in Ivanhoe Mines Ltd., its partner in the Oyu Tolgoi project in Mongolia.

Rio will buy 15 million shares at C$16.31 each, the London- based company said today in a statement to the Australian Stock Exchange. That will lift its holding 2.7 percent to 22.4 percent.