Rio Tinto's Oyu Tolgoi copper mine in Mongolia has been delayed after the nation's government said the terms of the project financing secured for the underground development will need parliamentary approval.The Mongolian Parliament is currently in summer recess and the approval process may take some time to work through. "Rio Tinto remains committed to working with the Government of Mongolia to secure project financing," Rio said."However, in view of the current uncertainty, including continued discussions with the government on a range of other issues, all funding and work on the underground development will be delayed until these matters are concluded and a new timetable has been agreed." The company added that it will focus on the ramp-up of the open pit mine and sustained export of Oyu Tolgoi concentrate to customers in order to deliver the associated benefits to stakeholders.Shares fell 0.03% to 2,921p at 10:02 on Monday.