Rio Tinto has warned customers of delayed copper deliveries from its Mongolian mine in the latest sign that the coronavirus is affecting the Australian companies’ product flows to China.

The spread of the virus into the northern Chinese province that shares a border with Mongolia prompted a ”state of emergency” to be declared in Mongolia’s Khanbogd province on Tuesday, where Rio’s Oyu Tolgoi mine is located.

Copper from Oyu Tolgoi is typically trucked across the border, but Rio said increased restrictions designed to halt the spread of the disease had affected product flows.

”Rio Tinto confirms there has been a slowdown in copper concentrate imports crossing the Mongolia-China border related to coronavirus containment efforts by local authorities,” said a spokesman for the miner.

Copper is often seen as a bellwether for the global economy, given its use in a wide range of manufactured goods. The metal was fetching more than $US2.80 a pound in mid-January but fell below $US2.55 in early February on signs the coronavirus would force industrial shutdowns across China.

Copper fetched $US2.60 a pound on Wednesday. (Financial Times)