Significant volumes of unwanted Russian-origin copper have been deposited in London Metal Exchange approved warehouses in Germany, the Netherlands and Taiwan since the middle of September.
Some of the biggest copper mines in the world are turning to different ways to get their metal to port after an increase in train robberies spurred the suspension of rail services in northern Chile.
The remarks come two days after global miner Anglo American expressed concern that the Peruvian government might be reconsidering the company's license.