Volkswagen said its work with RCS will focus on auditing suppliers for conformance with human rights, safe working conditions and environmental protection.

"The cooperation with RCS Global helps us to better understand which raw material sources and suppliers are in our supply chain and to measure their responsibility performance. In direct contact with our sub-suppliers, we can better explain and monitor our expectations of responsible sourcing and better follow up on agreed measures following our sustainability audits," says Ullrich Gereke, head of Procurement Strategy.

RCS Global has developed a supply chain analysis system that tracks adherence to sustainability criteria at sub-suppliers, refineries, smelters, mines and recyclers.

Volkswagen noted that through its cooperation with RCS Global, the carmaker has already been able to identify 134 sub-suppliers and 18 mines in the Volkswagen Group's battery supply chains, and the majority have already been audited.

Dr Nicholas Garrett, chief executive of RCS Global Group, says: "The expansion of our partnership with the Volkswagen Group, one of the world's leading manufacturers of automobiles and commercial vehicles, demonstrates the positive impact corporations can achieve when acting decisively in support of responsible sourcing.

"RCS Global is the key responsible sourcing partner to industry in the rapidly expanding EV battery supply chain. Our partnership is another important milestone in our impact-driven journey."

In August, RCS Global Group launched a copper mark assessor, with Rio Tinto's Kennecott mine, the first to be awarded the mark. The organisation is also active in covering cobalt, copper, tin, tantalum, and tungsten activities in the DRC and Rwanda.