According to Reuters, four sources with direct knowledge of the matter said copper and cobalt produced by companies including Glencore and Luoyang Molybdenum were stuck in Kolwezi, Democratic Republic of Congo (DRC), as truckers began a strike in late October.
Two of the sources said there were already 2,700 trucks carrying around 89,000 tonnes of copper stuck in Kolwezi.
A strike could strain global supplies of copper, which is used in power generation and construction, and cobalt, which is used in rechargeable batteries to power electric vehicles. Both metals are critical to the energy transition.
The truck drivers, who transport the ore from Kolwezi to Zambia, then to coastal ports, where it is shipped to consuming countries such as China, are asking logistics companies to pay an additional $700 in risk allowances per trip, the sources said.
The strike has already prevented ore from leaving Congo produced by major suppliers, including Ivanhoe Mines' giant Kamoa Kakula, Luoyang Molybdenum's Tenke Fungurume, Glencore's Kamoto and Huangang Mining's Mashamba West.
Glencore declined to comment. Luoyang Molybdenum, Ivanhoe and Huangang Mining did not respond to requests for comment.
"Truckers want incentives, incentives to do business in Congo, and they want hazard pay on top of their existing wages," said Hippy Tjivikua, group CEO of Walvis Bay Corridor.
Hazard pay is compensation for the risks associated with trucks being robbed of high-value copper and cobalt materials.
"It affects most of the supply routes. I can't say the cargo is completely blocked, but most mines are not able to unload or pick up."
The DRC is the world's third-largest copper producer, accounting for 10.4% of the 22 million tonnes of mined copper supplied globally last year, according to the International Copper Study Group (ICSG). The Democratic Republic of Congo is also the world's largest producer of cobalt.
Last year, Congo supplied 76 per cent of the world's cobalt, or 141,500 tonnes, according to Darton Commodities, a mining and metals company.
A Reuters poll this month showed the copper market is expected to have a small surplus of about 112,000 tonnes this year, but there could be a shortfall if the strike drags on.
