The Anglo-Australian miner said the movement of goods and people, including overseas contractors and technical experts, had become more difficult in Mongolia and across the Chinese border after the first case of the coronavirus was recorded in the country and the government took action to limit its spread.

As a result, work on a multibillion underground expansion of the Oyu Tolgoi copper mine had been slowed, Rio said.

“This is slowing down construction activity at the underground project,” said Arnaud Soirat, the head of Rio’s copper and diamonds business. “It is too early to determine the impact of this and the team is doing all they can to minimise the disruption in a challenging environment.”

The company said it would update the market once more information was available and that operations in the open pit at Oyu Tolgoi and deliveries to customers in China were continuing as normal.

The underground expansion of Oyu Tolgoi is Rio’s most important growth project and will increase its production of copper at a time when the shift to renewable energy is driving growing demand for the metal for use in electric vehicles and wind turbines.

But the project, aimed at increasing output to more than 500,000 ounces a year, has been dogged by problems.

Last year Rio warned of a 16 to 30-month delay to first production — which is now expected between May 2022 and June 2023 — and a cost blowout of $1.2bn-$1.9bn. The company blamed difficult ground conditions.

Rio expects to complete a new mine design by the end of June and reveal new cost and timing estimates in the second half of the year.

Shares in Rio fell 5.8 per cent to 3,082p, close to a three-year low.

“This is likely to be the first of many changes to the underlying project path, production profile and capex spending across not just Rio Tinto but the entire mining industry,” said Tyler Broda, analyst at RBC Capital Markets.

“Balance sheets in the sector generally remain very strong, but like almost all other industries, the potential for operational stoppages is likely to create a material build of working capital. We see the miners generally being in a strong relative position to cope but clearly these are volatile times and estimates and forecasts are likely to be changing rapidly.”

Canadian group Lundin Mining has announced the suspension of construction at its Neves-Corvo zinc expansion project in Portugal because of travel restrictions related to the coronavirus.