Mining and refining companies, including Glencore and Umicore, have said new EU rules aimed at limiting exposure to cobalt could “decimate” the industry in the region, derailing efforts to reduce dependence on supplies from China.

In a letter to the European Commission, executives said a proposal to set a maximum limit of cobalt that can be inhaled at lower levels than in China or the US was already deterring investment. This was undermining attempts to build a local supply chain for a metal that is crucial to industries from electric vehicles to defence, they added.

“The damage is already being felt,” 12 executives and industry bodies wrote to commission president Ursula von der Leyen ahead of a vote of EU member states on the cobalt exposure standards on Wednesday. Companies “are diverting investment away from the EU” as a result of the plans, they said.