Turquoise Hill said the suspension was effective December 1 and was due to a new requirement at the Chinese-Mongolian border to utilise one joint coal and concentrate crossing route.

“The new requirement has led to safety and security concerns as well as unreasonably long waiting times to cross the border,” Turquoise Hill said.

“Oyu Tolgoi is seeking to clarify the requirements with the relevant authorities in Mongolia and China.”

The company is unsure how long the suspension will last at this stage.

The mine sits only 80km north of the Mongolia-China border.

Oyu Tolgoi has produced 156,000 tonnes of copper-in-concentrate so far this year and is on track to achieve the upper end of 2016 production guidance of 175,000-195,000t copper and 255,000-285,000 ounces of gold.

Turquoise Hill owns 66% of Oyu Tolgoi with the Mongolian government holding the balance.

Rio owns 51% of Turquoise Hill and manages the Oyu Tolgoi project, including the $US5.3 billion underground expansion which recently got underway.

Shares in Rio closed 1.1% lower at $A58.04 on Friday.