NEW YORK ( TheStreet) -- Shares of Ivanhoe Mines ( IVN) are surging ahead by more than 12% on Tuesday morning as a battle is being waged with joint venture partner Rio Tinto ( RTP) over control of a copper mine in Mongolia. Shares of Ivanhoe were among the biggest gainers in the market on Tuesday morning after the mining company said it was sticking with a controversial shareholder-rights plan that allows it to sell more than 5% of its common shares to a major mining company. Ivanhoe gave Rio Tinto 60 days notice of its intent to implement the plan on Tuesday. Mining players including China's Chinalco have expressed interest in buying a minority stake in Ivanhoe Mines, according to published reports. Rio Tinto, the existing joint venture partner with Ivanahoe, has already invested significantly in the Oyu Tolgoi project in Mongolia. Rio Tinto owns just under 30% of the mine. The mining giant claims that the shareholders rights plan being implemented by Ivanhoe breaches its private placement agreement, which includes the right for Rio Tinto to increase its stake in the joint venture to 46%. The plan was approved by Ivanhoe Mines shareholders in April, as well as by the company's board, except for Rio Tinto's board representative. Ivanhoe released a statement on Tuesday saying that the company, "intends to continue to work in good faith with Rio Tinto to realize our shared objective of bringing the world-class Oyu Tolgoi mine into production in 2013." Ivanhoe Mines said it is seeking additional financing options for the copper-gold mine. -- Written by Eric Rosenbaum from New York. Follow TheStreet.com on Twitter and become a fan on Facebook.