Mongolian officials ended their first shareholders' meeting with Rio Tinto officials on Thursday without reaching agreements and criticizing the mining giant's unpreparedness.

The meeting began Wednesday afternoon to discuss Oyu Tolgoi LLC, a Mongolia-Tinto joint venture developing a large gold-copper mine in the south Gobi region of Mongolia.

The two sides agreed to meet later this month.

Mining Minister Gankhuyag Davaajav said at a press conference after the meeting that the Rio Tinto manager working for Oyu Tolgoi LLC did not read the investment agreement or feasibility study.

"Therefore, I told them to change the situation in the next talk," the minister said.

Batbayar Nyamjav, the economic development minister, also warned the investors to "respect Mongolian customs and traditions and follow Mongolian laws and regulations."

In response, Rio Tinto Copper Chief Executive Andrew Harding said in a statement that the project construction was finished "ahead of schedule and in line with the budget submitted to the Oyu Tolgoi board and government shareholder representatives".

"We produced our first copper concentrate last week, and remain on schedule for commercial production in the first half of 2013," Harding said.

He said, though, that "substantive issues about the ongoing development have been raised by shareholders."

Oyu Tolgoi CEO and President Cameron McRae also said that Tinto "has always been fully transparent with all our shareholders regarding our project's finances, costs and operations."

Rio said that the remaining construction of the project cost 6.2 billion dollars, which was in line with the budget submitted to the Oyu Tolgoi board and government shareholders in December 2010. The Mongolian government claims initial investment has exceeded the budget.

Mongolia, which holds 34 percent share of the Oyu Tolgoi LLC, has long hoped to increase its ratio in the development of the giant copper-gold deposit and get more economic benefits.