“This award represents an important milestone to our business in Mongolia bringing our total number of mines to three,” Leighton Asia managing director Hamish Tyrwhitt said.

“Our work in hand at Leighton Asia has now reached a record level of $A6 billion.”

MEC chief executive officer James Schaeffer Jr said the contract was the completion of a major step forward in the implementation of the company’s business model as an energy and resources developer.

“Our selection of Leighton as mining contractor will assist in the efficient and professional development of our initial project at Khushuut and demonstrates MEC's commitment to building professional and local relationships for further projects,” he said.

The mine holds 149Mt of coking coal resources, but this is only within 600 hectares of 330,000ha of the MEC’s concession areas in western Mongolia.

MEC also recently upgraded a 310-kilometre roadway from the mine to Xinjiang, China.

Leighton shares are down 10c to $32.29.