April 8 (Bloomberg) -- Ivanhoe Mines Ltd. said construction of a $5.5 billion copper and gold mine that it's developing in Mongolia is set to begin.

The Oyu Tolgoi copper project is scheduled to start in 2013 and will require investments of $758 million this year, Ivanhoe Chairman Robert Friedland said today at a Santiago conference.

Rio Tinto, the world's third-largest mining company, said last month it would boost its stake in Ivanhoe as part of an accord to finance equipment for the project in Mongolia's South Gobi region.

Oyu Tolgoi is the world's largest untapped copper and gold deposit, holding as much as 81 billion pounds of copper resources and 46 million ounces of gold resources, Ivanhoe said on its Web site.