The companies have purchased 5,000t of the concentrate from the mine on a trial basis.

Oyu Tolgoi is a joint venture of Turquoise Hill Resources and the Mongolia Government with 66% and 34% stakes, respectively.

Rio Tinto, which owns majority stake in Turquoise Hill Resources operates the mine.

The copper from Oyu Tolgoi was shipped to Mitsubishi Materials’ Naoshima Smelter and Refinery earlier this month.

Mitsubishi Materials raw materials department general manager Tatsuya Inoue was quoted by Reuters as saying: "We purchase over 60% of copper concentrates from Chile and Peru and we want to lower the degree of dependence on South America."

Mitsubishi imports about one million tons of copper concentrates each year with around 70% being sourced from Chile and Peru.

Inoue said: "We have not made any decisions on contract, but we intend to talk with the producer about a long-term contract as early as early next year."